I don't remember for sure what projects my phone was working on when I noticed the issue. It just seemed that all tasks regardless of project progressed very slowly when running three simultaneously, as I was observing for several weeks.

My phone is actually working on OET now, the only task, and at this point in time it's at 89% after 08:34:14 and fairly quickly progressing at a rate of about 0.1% every 15 seconds on average. It was sent on the 24th and the deadline is comfortably December 3.

Given my original issue of results not sticking around much longer than a day and the event log not keeping events longer than a couple hours, I have no idea if any of them have failed. The few I have seen that weren't late, as I recall, were valid.