This is not a bug, only a false message. I tried submitting a gallery item, and I got this warning :
Upload Temporary Restricted
You cannot post more than 3 submissions in 24 hours.
But in fact five images per twenty four hours is the cap. At first I thought perhaps I was being punished, but I had
done nothing to warrant punishment, and it had been twenty four hours since my first upload of the previous day, so I
wasn't sure what was wrong. So I waited twenty four hours since my last
upload of the previous day, and everything worked fine. I still get that message after my latest five uploads, so it
wasn't a single time thing.