I was drag/dropping screenshots which started uploading but it took a bit long and then I got a pop up saying permission denied. Tried converting them to jpg, selecting all three and dragging them all in. One got through but then I had permission denied again.
The files were all screenshots taken with scrot so had a long date/time filename.
Trying again:
Screenshot using local adjustments/dynamic range compression with lowered exposure
The blown sky after raising exposure and before attempting recovery.
The third image failed