Units Failing to Capture Territory

Game 2831093

Two times today (it has not occurred prior to today), I've had two units, first Militia then AC go through an enemy territory and fail to claim it.

This was not during day change so not a case of the territory rebelling back to previous owner (I know the time and did go back though newspaper to confirm). Simply unit walked through centre (dot intersection) and passed through it without capturing it.

AC in province BAKU at approx 3hr after server reset

Militia though GORGAN failed to capture it twice, once approx 3 hr before day end, then again 3.5 hours after day change for a second time when I sent it back to capture it after 1st failure.

Other units have successfully claimed territory before that, between these failures and since, and successfully captured territory, so I'm not sure why these failures occurred.