It only happens to me when my node is catching-up to the tip of the blockchain.
e.g.: when I just opened Bitcoin Core after a day/few hours of downtime.

If it's not the case, you can enable advance debugging with "rpc" flag, reproduce the issue and then consult your debug.log file for related entries.
e.g., start bitcoind with: bitcoind -debug=rpc

The message just below that screenshot is the actual error which should be enough to tell the reason why the server rejected the transaction.
That's mostly the reason why the earlier replies asked for the actual error message.

Electrum should be opened with those command line options.
In the terminal, open electrum with the "-D ELECTRUM_PATH" global command line option (command depends on how you installed Electrum);
e.g.: $ ./run_electrum -D ELECTRUM_PATH

A fresh data directory will be created; if you want to keep your old settings and wallet, copy it.

Try to send now.
The issue is now solved by Trusted Coin.

I looks like you meant "seed phrase" instead of "passphrase"; the 12-words that you should've copied.
If so, I'd suggest you to create another wallet and send all of your funds there since using that wallet could lead to loss of funds.

Like what happened, if Trusted Coins' server shutdown or became inaccessible; without the seed phrase, your funds will be locked up.

Seeing this reply after two years means that you remarkably haven't made an error that replaced the output's amount
or worse, sent to a "blackhole" recipient by typo~ing the pubKeyHash.

Do not rely on those server list sites, most doesn't actually check the connection with Electrum.
When it detected that it's online, it'll label the server as "OK" regardless if clients can connect to it or not.

Electrum should be able to detect if it's connected, see the previous replies.

Using "Open Wallet" menu isn't necessary, previously loaded/created wallet in Bitcoin Core wont automatically unload themselves.
Any opened (loaded) wallet will be automatically loaded when opening Bitcoin Core unless closed (unloaded) manually.

I'm not using the wallet server but in the desktop client, the feature in under "Tools" and only available if the wallet isn't watching-only.

You may have checked "Make Blank Wallet" when you created the wallet which produces a wallet.dat without any keys in it.
That obviously will disable "Create new receiving address" button.

Close that wallet and create a new one but do not modify the pre-selected options aside from "Encrypt Wallet" for your wallet passphrase.

Honestly, I never experienced this since I rarely use 1sat/vB and haven't consolidated UTXO in Sparrow.
I tried to reproduce it but it's limiting the fee rate to 1.1 sat/vB ("Create Transaction" is grayed out for 1sat/vB) if the software computed that 1sat/vB wont match to the absolute fee and size.

May be an issue with your input method because instead of 19YZECXj3SxEZMoUeJ1yiPsw8xANe7M7QR
KeyHunt-Cuda read it as 19YZECXj3SxEZMoUeJ1yiPsw8xANe7M7Q (missing the last character).
Or you didn't just mistyped the command in that post as well?

I tried to reproduce the issue but it didn't happen to me, the address is correct and key was found.

Just for convenience purposes and it prevents address reuse.
Once linked, you can easily select the user's PayNym to send to his unused address without requesting for new ones.

BTW, that's the behavior in Sparrow, IDK how it is in other clients.

Okay, Electrum is a good alternative anyways.

For clarification in Sparrow wallet's fee rate, it must be because the transaction isn't final which is generally lower in size than a signed raw transaction.
After signing it, click "View Final Transaction" and you'll see the correct fee rate that you've set in the send tab.
Optimizing it for "Privacy" could also meddle with the output amounts and fee.

Import it to non-descriptor Bitcoin Core wallet instead and those P2PK transactions should be scanned without issues.
That's if you're already running a full node or want to set-up one for that purpose.

You can also manually edit the absolute fee in Sparrow just like in Electrum's advance transaction preview.
Just make sure that the fee "Rate" above it wont fall below 1 sat/vB or "Create Transaction" will be grayed-out.

Now, this is an entirely different issue from your first post, I presume?
Because the command line doesn't show that it stopped after running for hours.

For that error, it's could be the issue when searching for multiple full addresses with Nvidia GPU, try to downgrade to v1.17.
Reference (issue #81): https://github.com/JeanLucPons/VanitySearch/issues/81#issuecomment-745085166

Probably, it could be the difference in default "gap limit".
Electrum only generates 20 addresses beyond the last used address while Bitcoin Core has 1000.

For example: for fresh wallets, if the receiving address is at 21th index due to multiple use of getnewaddress command
Electrum wont be able to see it until some of its first address received btc.

You can try to increase Electrum's gap limit to match Bitcoin Core's default by using a command,
Open the console and enter ("View->Show Console" to enable the tab):

It will work if OP is using the same IP address as before and previously logged in using that device,
otherwise Blockchain will detect it as new device and ask for log in verification, it's extremely easy to test that behavior actually if you have an account.

Users who reported that it worked must have a static IP or have had the same IP address when they previously logged in to the app.

Output Descriptors are quite new and not all wallets support it, the two that I know are Bitcoin Core and Sparrow.
That video used Sparrow wallet which has good features and descriptor support.

Most wallets as of now, store the keys in a different way.

The issue is solved, he was using an old version of the app.
Tip: Try to read a few replies back and at least a glimpse of all replies the next time you plan to reply to a thread   

Quote of OP's reply: