Preview can't modify image?

I stuck an image into DT3 knowing that I could open it externally and crop it. I can do this with Acorn with no issues, but when I tried this in Preview, it gave me the following message:

I’m assuming this is an Apple thing, but as Preview is usually already running on my Mac, it would be faster to use it. Anything I can do to fix this behavior?
I’m still on Mojave.

Not directly, no.
You can only put the files in another database.

And yes, this is an Apple issue to keep people from modifying things in the User Library (which is where the Global Inbox - or potentially other databases, though we don’t recommend putting them in our App Support folder).

OK, so the issue was that it’s in the global inbox. I moved a test image into a database and was abel to use Preview for the edit. Thanks for the clarification!

No problem. Yeah, that’s been a longstanding behavior of Preview.