Thanks LucD, I will try that.
Regarding your question, I will have to go through the events in more detail. But before that, let me just highlight what I'm seeing:
Script looks at snapshots for VM #1
<User account X selected for all snapshots. Seems correct>
Script looks at snapshots for VM#2
<User account Y selected for all snapshots. Seems correct>
Script looks at snapshots for VM#3
<My account selected for all snapshots. Seems correct>
Script looks at snapshots for VM#4
<No snapshots>
Script looks at snapshots for VM#5
<My account selected for all snapshots. Definately INCORRECT>
Script looks at snapshots for VM#6
<User account A selected for all snapshots. Seems correct>
Script looks at snapshots for VM#7
<User account B selected for all snapshots. Seems correct>
Script looks at snapshots for VM#8
<User account C selected for all snapshots. Seems correct>
Script looks at snapshots for VM#8
<User account D selected for all snapshots. Seems correct>
Script looks at snapshots for VM#9
<User account C selected for all snapshots. Seems HIGHLY IMPLAUSIBLE>
And so forth. There seems to be a trend that a user account that had been correctly matched to snapshots, is subsequently incorrectly matched. If it's selecting the wrong account, I suspect that means it's failing to find the correct snapshot task, and my filter criteria are not adequate, IMHO!