The particular unit, of which the log is shown in the screenshot, was entrenched in a village, but was actually little "threatened" ( DF or IF) nor had suppression (0). It also showed "halted" exclusively for a duration of about 2 hours, with updating intervalls of between 10 to 15 minutes. A particular feature of this situation, was that it was rather "isolated" in the area, no apparent LOS to friendlies (combination of terrain + weather setting), although beeing in effective command range (~ 1km to Btl HQ). After any enemy units got out of sight (retreating or moving away), log entries vanished entirely. (reverted back to waiting/entrenched)
So this particular "halting" might have been triggered by (feel of) battlefield isolation.
Another infantry unit, well entrenched in a woods very much stood firm, in the face of about 3 to 1 odds attackers, but started to "halting", when another enemy unit appeard on one flank. Soon after, this unit retreated in actually good order (little suppression, good cohesion, negligible losses taken). This unit was framed by friendlies in good order. A particular feature of this retreater was, that it had requested emergency supply, shortly before the orderly retreat.
Here the flank attack, as well as going low on ammo, might have been the trigger.
Both mentioned units had no orders been given ( I simply left the whole force alone, for testing purposes. The superior player unit HQ, was a divisional HQ).