The title says it all really.
When I set an assignment up as a single activity format everything else seems to work fine but the PDF editor fails to load. There's just the spinny thing rotating at the top left forever.
There is a Launch PDF editor... button on the right but clicking this does nothing.
Change to another course format and the editor loads as expected.
This is on Moodle 3.4.3+
After changing back to another format the PDF editor loads again. However, when saving changes, an error message pops up saying:
"Coding error detected, it must be fixed by a programmer: Improper use of the assignment class. Cannot load the grade item."
Then the screen is greyed out and it gets stuck with the message "Saving Changes" and an infinitely looping spinny thing again.
If I refresh the page or close and open again, any changes I made do get saved.
There was a long-lasting bug could be found in most all 3.4 updates. Apparently, works fine now with 3.5.2. But yet, I experienced so not with all the files, just certain ones. And when I tried to upload them to another tool to edit pdf they didn't load as well. But only if trying to open with Moodle was the first step taken