I sent a message to staff from the topic I just posted on the Australian group. Here is some more info. The message is titled "Acsc 259 1/0½ KGV Issue Of 1950" - http://goscf.com/t/74221
Using Firefox 80.0.1 on Windows 10.
1. start editing a new post.
2. open the upload window but go straight back to main editing window without selecting or sending an image to SCF. (I did not try selecting a file and going back to the editing window without uploading it.)
3. at this point I can no longer access the upload window. The link doesn't work. If I close the main editing window, I can see the upload window but it is totally inoperative. I will need to force close it or reboot.
No problem was experienced when I actually uploaded a file in step 2.
I went through this process again using on Testing channel and the problem replicated the same way.
I then tried it again on the Testing channel using MS Edge without problems.
This is not an urgent problem (unless, I guess, you don't know about the problem).