Cloudflare is basically out of LQ's reach.
Of course it would be in jeremy's power to do something about it, but he hasn't even commented on the flood of recent complaints.
They check IP's - and if your currently used TOR exit node is on some blacklist, bam, you're out. Doesn't matter if you're logged in.
The Tor Browser Bundle is also set up to periodically and automatically change the onion route iirc.
My experience with other sites was that they sometimes work through TOR, sometimes not. Have to try and try again until you hit an exit node that is not (yet) blacklisted.
Blame it on people who (ab)use TOR for nefarious purposes, like trolling until their IP (in this case the exit node) gets blocked and added to some blocklist.
And recently we found out that cloudflare also scans the content of data submitted, and applies a ridiculous level of "better safe than sorry" to block "suspicious" content.