Right... and it will display "watching only" beside the wallet type next to the wallet name (at the  title bar on top).

The links in my reply?
It's working at my end, I guess your ISP is blocking GitHub or some other reasons why you can't access it.

Ah, so it's basically something similar to v0.30 and v0.34's compatibility-breaking update to the key derivation.
But unfortunately, I don't know if there's another update like that.

You can try to ask the developers themselves from electrum's Github repository.
Specially ecdsa (ThomasV) and SomberNight. (they have email address in their GitHub profile)

That can't be.
Seed phrase has been compatible to the latest version since it's implemented,
even seed phrase from v0.30 will work with the latest (but wont restore the correct keys).

There are other wallets that use(d) their own implementation of seed phrase/mnemonic backups that aren't BIP39.
Example is blockchain.info's old account recovery phrase; you might have used other wallets aside from Electrum.

You mean can be downloaded from electrum.ecdsa.org?
IDK but this is the oldest archived page of the site's download page: web.archive.org/web/20121109025628/http://electrum.ecdsa.org/download.html

Those two are the only option if "Trampoline Routing" is enabled.
You can customize the remote node once you've disabled the said feature in the settings.

However, I haven't succeeded yet with creating a channel between two Electrum wallets.
You can try though - by providing each other's 'Lightning Node ID' as the "Remote Node ID" (Wallet->Information) followed by the IP address and port.
eg: 02d50fdf1806b54aee46a0ed8c6d8512bee87e88e25029f3384a983c43c5d6a16c@111.111.111.111:9735
But like I've said, it never worked at my end.

The two things that you may have missed are:

• Lightning should be enabled in the menu "Wallet->Information" if it's not ticked at least once yet (if it's created by an older version).
• The wallet's script (address) type should be Native Segwit ('bc1' address), other types including 2fa aren't compatible with Lightning.

Did it happen even in your latest attempt?

Anyways, so the symptom's timing varies, interesting...
Are you sure that you're the only one who have access to your computer(s)?
Because it looks like someone has been creating the watch-only wallet by importing that address while you're away.
That's the only logical answer that I can think of.

I'm wondering, are you perhaps using "Deepfreeze" (wiki) or other similar software?

That's the correct pair, so it's working as intended.
IDK what that test is for though since the issue is about 'imported' wallet turning into 'imported - watching only' wallet.

That just proved that your Electrum is working as intended.
Pmalek also instruct you to check if the private key that you'll get from "1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm" is the same as the private key that you've imported.
('1EH' is publicly known, no need to censor that address)

The shortcut is to open the 'Addresses' tab ("View->Show addresses" to enable the tab), the right-click on the address and select 'Private key'.

So you're abroad?
It may be the ISP, if the solution above didn't work, try to change your DNS.
e.g.: into google's (8.8.8.8), cloudflare's (1.1.1.1) public DNS or others.

There are a couple of online tutorials about 'how to change your network's DNS'.

The problem is Electrum is not a company or an entity, it's an open-source project that's being maintained by volunteers.

If you want to hear-out the developers currently working on the project, you can reach them in Electrum's repository in GitHub:
Repository - github.com/spesmilo/electrum | Contributors - github.com/spesmilo/electrum/graphs/contributors

That's a very famous topic that's been discussed quite frequently.

If you need more responses to that question, read these old threads:

• 2012: What happens when all bitcoins are mined?
• 2013: after all BTC has been mined, what then?
• 2019: How will Bitcoin survive after all 21M coins have been mined?

Any follow-ups or you'll just leave it unresolved?

If using a 'blockexplorer' doesn't concern you (privacy concerns), you can lookup that address and see if there's any unspent output(s).
If there's none, then it's indeed Bitcoin Core's issue when it scanned for wallet-related transactions.
e.g: blockstream.info (check if it has any "CONFIRMED UNSPENT" outputs).

It's also possible that the transaction that spent the funds wasn't mined and dropped from the mempools.
Better do a rescan to be sure.

Take note that you can't use the command above if your blockchain is pruned,
Go to your Bitcoin Core's 'Settings->Options...' and see if "Prune block storage to" checkbox is enabled.

Everything is in the software's code.
There's no "who", just the miners who compete for the winning blocks.
"when" is completely 'average', there's an ever-adjusting 'difficulty' that ensures that blocks can be mined in an average of 10minutes.
Each block's reward is currently 6.25BTC (+fees) which was 50BTC when Bitcoin was just released because it halves in every 210,000 blocks.

Pretty much everything covered in this 'the Bitcoin Wiki' article: en.bitcoin.it/wiki/Mining

Better than asking here in the forum where there's no official CMC representative.
Users will most likely answer with guesses and other non/related stuffs.

Bitcoin Wiki says, find a way to contact this guy: https://github.com/kallewoof
There's a Twitter link in his GitHub profile page and he's active there.

Try asking their support instead, there's an option for "Questions" on the number 12 in the list of request types.
Link: https://support.coinmarketcap.com/hc/en-us/requests/new

Unfortunately, there's no info in the 'Trending' page nor in their FAQs about the requirements for getting into the 'Trending Cryptocurrencies'.

Judging from the source code, it's supposed to be a Capcha that can't seem to load.

I don't know if it's legit but the stats that states: "642 months" to break even with your initial deposit is already a sign that it's not worth it.

Looks like someone has reported him, he's already auto-banned by a Mod, it's logged in the forum's deletion log: Archive: bitcointalk.org/modlog.php

A well-written single-address client will do that (send the change to the same address), but most wallets will use a "change address" for the remaining 0.5BTC.

I guess that API works like coinb.in which requires you to manually add a 'change address', or it'll use the remaining funds as fee.