It's odd to see so many suddenly having this issue, and I might be able to offer a more liberating one. Everyone's situation is different, but twice yesterday my colleagues had this exact problem. I suggested they clear their cache and browser history, and then to close their browser (Chrome in both cases) and reopen a clean window. In both cases, this was an instantly effective solution to the problem.
I hope this helps.
The issue is on the back end of Steem not the frontend of SteemIt. Bandwidth regenerates and the amount available constantly changes.
I think you might have seen a coincidental "fix" from clearing cache.
(I was getting this error going directly thru the steemd)
That's possible. Multiple occurrences of success by clearing cache would tend to contradict the likelihood of coincidence. From a statistical perspective, I've only seen the problem and solution twice, which leaves plenty of room for coincidence.