Anki doesn't add new cards, no error message, work is just irretrievable

Hi - Anki is a useless time stealer at the moment. It doesn’t add any new cards - I create and add them as I always used to, but they don’t show up in the deck at all - never, all work is just lost without any error message.
I haven’t used Anki in a while and updated it, but I am desperate because hours of work are lost and I can’t use Anki at all like this.

I have already tried everything I found in the suggested troubleshooting guides.

Any advise would be appreciated!

Siehst du die erstellte Karte denn in der Browse-Ansicht?

Please, read this: