It looks that sometimes I can have it open for longer than 30 second with no issues, but other times, independently of how many seconds passed since I opened the File Manager, when I am uploading a file it displays this darkened login screen. I had uploaded this file successfully like, 10 seconds before.
I always need to have the open file manager button in another tab so that I can open it again because it broke.
That’s a known issue that developers couldn’t determine the reason for it.
This just happens the first time you login to the file manager, so when you hit the button again, the file manager should be stable