Some news. I'll also say that I've sent them an additional screenshot from Yobit, showing the withdraw. I don't know if it has sped up their reaction, but an email came from them a few days ago. They thanked for cooperation, released the transaction and the money came into my Spectrocoin wallet. Next to that they wrote: "please be advised that you can no longer receive payments from YoBit.net platform. Further payments received by you from this platform will no longer be accepted."

Another email also came saying "that your verification needs to be updated", even though I had already done it a few weeks ago. So I went through the whole questionnaire again, just by clicking 'Next'.

So I conclude, as many of you here have surmised, that the main trigger here was the sender and his reputation - shady Yobit. And at the same time, this is a tip for those who still use Spectrocoin and Yobit and are not aware of the reputation of the latter - these two companies can not be intertwined in any way. Avoid making transfers from Yobit to Spectrocoin, as you may have problems, bigger or smaller. This is more for newcomers. Experienced users who know Yobit better could tell more about it and transfers from it to other wallets.

So the problem is partially solved, because my desktop static IP is still blocked by Spectrocoin. I have asked them about this twice already, and I have emailed them again recently, but I have not received a reply yet. When I have any news (including news about no news), I will add more here.

Thank you all for your advice and comments.