I can't increase or decrease the progress of the manga in my reading list. I tried an un-cached refresh and it still didn't work.

Had the same problem on friday but after clearing cookies/cache and everything it worked again...

omg, i was pretty upset about this error
and your cure does work!!
thank you so very much

fixed it in firefox by clearing:
browsing and download history
cookies
cache
offline website data

through the clear recent history tool. clearing just the cache didn't work so its probably some FF bug.