Theme extension block doesn't show up in editor

Hey,

I am currently working on an app with a theme extension. The goal is to have a block that I can place inside the product information section.

For whatever reason when I use shopify app dev and then go to the editor I can’t find the block, although the app is installed/deployed.

Instead I get this:


”Something went wrong. Try clicking Add block again.”

That’s all. I don’t get errors or logs anywhere and tried now different things for hours.
What could it be? I sometimes red it’s the target that could be wrong, but I tried out everything.
How can I check where the error lies?

The funny thing is that everything worked just yesterday and now I turn it on again and it’s just not there anymore. So I can’t work on the frontend.