UD Monitor作者の見解出てる I should also make people aware that using the backup option in UDM can itself sometimes cause WUs to abort - something I discovered and reported many moons ago.
If it works for you, that is fine, that's why it was never removed.
Also the fact that you can get through an aborted WU suggests the WU itself is not at fault and more likely the ligandfit app is somehow getting confused after running for a period of time. Investigations by UD is still on-going.