Does a mass update end on the first failure? Out of 581 results I got 58 successes and 523 failed, and it gives an expected error, but more than 58 should have succeeded, and indeed when I go to the individual records and perform the same actions manually, edit then save the transaction without any changes, I get the expected results with no errors. Why didn't my script catch these in the mass update, even though they were valid results? How do I troubleshoot?

we have noticed behavior where mass updates fail at random. I think there's a defect for this. Also -- we have noticed that mass update search results differ from regular search results. Because of this, we've started utilizing scheduled workflows to do mass updates more reliably. 😕