Well, that's strange because there is a key called bibase in my Feeds/API list in Zotero Settings. I've tried to revoke it and create again several times, without any effect. Can the problem be caused by underlyings in my nickname or group name?

I don't know what goes wrong... I createad a bibase key with default permissions, than typed https://bibbase.org/zotero-group/a_marko/birds_of_russia&msg=embed Than I recieved a message "Your Zotero collection could not be retrieved. Please try requesting a new Zotero key using the link on the BibBase homepage" and nothing else...

Hi Christian, thank you for elaborating the issue! Unfortunately, I haven't noticed any differences yet: most part of the library is still invisible. Even more, now I don't see the green panel with embedding suggestion when I choose my zotero group for generating (here is the link: bibbase.org/show?bib=https%3A%2F%2Fapi.zotero.org%2Fgroups%2F326590%2Fitems%3Fkey%3DaeNBZCKSTCeK3MEV89bpsb9v%26format%3Dbibtex%26limit%3D100 ).