Image Upload stuck

Hey guys,

right to the point my problem:

When uploading images for cover or avatar the upload is stuck after the progressbar finished.
Before that the problem even was an error “Invalid image” but i was able to solve this issue by testing all plugins for a conflict and deactiving the troublemaker.

I already:
– deactivated everything but UM
– used twentytwenty
– uploaded the image via the wordpress media library (no errors here)
– went through the “image uplaod troubleshooting page”

Wordpress 5.3.2, UM 2.1.5

Thank you for reading.