Same here (once I'd worked out whatr FF and GC were). Something odd in Firefox I guess.
not working, only files were uploading not entire folder.
Folder upload only works if contains less than 100 files.
I'm trying to drag and drop the build folder of a small react app and it doesn't let me drop it in the web interface. Seems to be less than 100 files in the directory... Any idea what the problem might be?