Oh yes... multiple times, and following a suggestion found on another thread, I even sent them a support ticket in russian (using google translate).

No reply so far except from the very first ticket to which they replied "check your transaction".

Thanks for your wishes though :-)

Thanks everyone for your replies.

No, I didn't take a screenshot of the first generated address - something wise indeed to do with a sizeable transaction, but it never occurred to me.

When I decided to send another 0.1 transaction, my rationale for it was - if this small transaction also is not credited, then their ETH network is just congested. But unfortunately, a new ETH address was generated as soon as I opened the wallet again.

The new transaction (the one that succeeded), just for reference, is this one:
0x791e76c8f10d6592d17686529349b358a73b7474e39ce5cbdae25b8174971403

Now - could I have made an error? Possible (although unlikely, I obviously copy/paste addresses when making transactions).

But what are the chances that I would randomly select a newly created, valid, never used ETH address?

In any case, I think my request makes sense: YoBit has the private key for the generated addresses, so I'm just asking that they check whether the address I sent the ETH to matches their private key.

But they have never agreed to do that.

What happened::
It's sad that my first message on this forum is a scam report, but alas  
On Jan 15th I sent 10.1 ETH to the automated address generated by my ETH wallet on Yobit.
(addr: 0x7b5019c816a4cac43529bac1ac63e49590bbf67e)

They were never credited. Subsequently, just to try if it was a general delay with Yobit, I sent a small transaction - 0.1 ETH and the wallet generated another address. This time the funds arrived timely.

Of course both times I copy-pasted the wallet address and checked it multiple times.

I contacted support and a week later I received a 1-liner: "check your transaction". Really? Do you think I didn't? I'm posting this here so that the whole world can check.
Scammers Profile Link:
https://bitcointalk.org/index.php?action=profile;u=406594
Reference Link:
Amount Scammed:
10.1 ETH
Payment Method:
ETH transaction
Proof of Payment:
ETH Tx Hash:
0xb9484c29705ddb0284a4b91c97f34457ed2ec93c6fba6d5b42fb473600a8a148
PM/Chat Logs:
This shows the support tickets I have opened and that were never answered
https://imgur.com/a/MPup7
Additional Notes:
This seems to be exactly the same situation described here:
https://bitcointalk.org/index.php?topic=2831618.0

What's happening with Yobit? Are they hoarding all the ETH deposit above a certain threshold?