cloud upload error

Hi,
So far, it wasn't a big problem, more of an inconvenience, and I haven't mentioned it before. But now I'm experiencing a bug that's preventing me from using the cloud.
The situation:
1. I am using the 32-bit MuseScore version 3.6.2.548021803 revision 3224f34 with Windows 10 Pro 1703 operating system.
2. I upload to the cloud directly from the program and I upload score updates this way too.
3. However, for a while now, I only see a blank window when uploading (see cloud-upload-step2).
4. There is no problem with the identification (see cloud-upload-step1), I also checked this by logging out and logging back in again.
5. The upload window can connect to the server: this is confirmed by the fact that the html source code can be displayed (cloud-upload-step2-source).
6. Despite the blank upload window, if I log in to musescore.com (i.e. using a browser, Firefox v115.0), I see that a new copy of the score has been uploaded instead of being updated. (But without any additional data.)
7. And if I try to update the score via the website (using a browser) (by clicking on the round arrows), the uploading application opens a standard Windows file manager window, but nothing happens after selecting the file.

The result: uploading is cumbersome and updating the score is impossible. At least for me.

If anyone has an idea I welcome that. Thanks!