If it was to get a mover into position for the next cue before its intensity came up from zero then it's possible they "turned on" automark. This is a marvelous feature which looks ahead in a cue list and sets a channel's non-intensity parameters (eg colour, position, zoom etc) when the movers are dark and before the cue brings up their intensity. You should see an "M" in the appropriate column for the cue in the PSD and the tombstone display will show "MK" for channels when you're in the cue marking them.

If you want the moves to be done with the intensity above zero then you can remove the mark flag on a per cue basis.

If it was to get a mover into position for the next cue before its intensity came up from zero then it's possible they "turned on" automark. This is a marvelous feature which looks ahead in a cue list and sets a channel's non-intensity parameters (eg colour, position, zoom etc) when the movers are dark and before the cue brings up their intensity. You should see an "M" in the appropriate column for the cue in the PSD and the tombstone display will show "MK" for channels when you're in the cue marking them.

If you want the moves to be done with the intensity above zero then you can remove the mark flag on a per cue basis.

I’m assuming I need to record (re-record) the cue with auto mark on for it to take. Or turn the mark flag on?

No, I don't think you do.

Simply turning automark on for the showfile (see below) will be sufficient for automarking to become active in the PSD. You can check by finding a Q with a mover and scan back from that Q to find the Q in which the Ion has automarked it (M flag set in a preceding Q).

No, you don't need to re-record. While running cues Eos looks at the setting and then automatically marks or doesn't.