cannot upload cover and profile pic

Every time I try to upload a cover or profile pic, they did not get displayed. I can select the picture and the progress bar is also shown up to editing/cropping the picture. The UI responds normal but it is just that the picture will not show up.

I have already tested with just the WP installation without changes to the default theme and no plugins modified to ensure no conflicts with 3rd party plugins but with no luck.

Are there any settings I can “tweak” to make this work? Or any debug messages I can look at with hope that the root cause can be identified?

Any help is much appreciated as I like this plugin very much. By so far I tested out different membership plugins, I am not getting the functions and features that I could find in Ultimate Member. It also integrates very good with the Sidebar Login widget.

Thanks for help in advance.

https://www.ads-software.com/plugins/ultimate-member/