The Wayback Machine does back up YouTube videos now, though (and has for the past couple years).

Err, it's now throwing a 504 Gateway Time-out error after a minute or two if I try to submit a job with categorization loops; confirming that that's the intended behavior?

Seems that was some sort of stale-OAuth-data issue on my end (at least judging from what fixed the problem for me). Sorry to've bothered you!

NVM, resolved for me now as well. (Going through the high-volume-activity OAuth process again apparently did the trick.)

Huh. I've even tried logging out and back in again, and I'm still running into the same bug...

Are we sure this's resolved, given that there's no way to test for it ATM due to its effect being masked by T334149?

It hasn't been resolved; IABot is still failing to expand category trees for categories entered as part of a batch job.

The bot's back to failing to expand category trees, after several months of expanding category trees properly.

The problem seems to've gotten worse; we've now got jobs stalling mid-run and never moving again, rather than waiting until the end of the run to stall.

Would this potentially be related to why the current five IABot batch jobs (11994, 11995, 11996, 11997, and 11998) are all currently stalled at zero progress, with the most recent batch-job edit being this one from nearly two weeks ago?