Generative Alt Text Credits Not Working in InDesign 21.2

Hi everyone!

I’ve just updated my Indesign to 21.2 (WIN11) because I wanted to check out the new AI-Feature to generate Alternative Text directly in Indesign.

I checked out my credits (500) before. But I can’t get my Indesign to recognize/ use these credits.

I already checked out my CC and signed in again but the Problem ist still there: the ALT-Text-Option remains greyed out (see attached image)

Anyone knows how to get around this?

Your help is much appreciated, thanks in advance.