Hello,
Thank you for your concern.
In our testing environment, the upload is working fine. Please have a look at this: https://www.loom.com/share/f053139788674f9983adb1166b27b8c5
In this case, Here is what you can do to check:
1. Please try switching to another theme, like Twenty Twenty-one
, and check whether the issue persists or not. If not, then it is the theme that is causing the error.
2. Deactivate all plugins temporarily except WPDM and see if that solves the problem. Then, activate plugins one by one to see which plugin is causing the problem.
3. Try one more time after clearing your browser, website, and CDN caches if you have any. You may temporarily disable the caching plugin for testing.
If still, the problem exists then please provide us with some additional details like screenshots or screencasts to reproduce the issue or represent to us what is happening so that we can investigate further from here.
We appreciate your cooperation regarding this.
Regards