One of six GPUs has 99% Util and 0 H/s, Progress gets stuck at 99%

[m0t0]

Also it can be too high clocks for gpu/ram or too low ram clock, also PSU problems can behave like that. What I would try is just to lower clocks a bit. Besides on your card's you should get a bit higher MH/s if they are on stock clocks (1000MHz?) so maybe cooling problems occur and they start throttling clocks and this sometimes is the reason for ASIC hang.

Thanks @KT819GM,
The clocks are set to stock values, no overclocking. It is reported as 925 Mhz on each.

I have been thinking it may be related to the temp control and throttling. There did seem to be some correlation to the card hanging after its temperature increased higher relative to the others around it, but I haven't been able to reliably reproduce.

I also tested using a lower temp value --gpu-temp-retain=45 to force the fans to be 100% and while it took longer (about 8 minutes instead of 2), #4 still got stuck. The temps, while not 45 were not too hot < 60.