You can duplicate this by playing against a brutal AI and repeat building likely any type of unit but it's more noticeable with the following units.
What you do is when you have secured the map and left an area for the AI to expand to but you have map control, you just hold your borders and repeat build a unit from a factory (listed below). You give the factory a set of queued up attack orders that take it through enemy territory and you build the units from the factory somewhat quickly with some caretakers. After this point you don't give any orders to any of the units from the factory.
What you will see is that some units even when not bunched up just stop in place and forget their queued up orders (maybe they got bunched up in a small group before possibly?). Also when they get bunched up in a bigger group by naturally engaging the enemy and as more units get to the same waypoint they get into a bigger ball/group. This is where more units will stop and forget their orders requiring you to select them and issue them orders and some (especially the sling unit) will stop shooting all together even when in range of the enemy. In fact many sling units just stopped attacking at all.
Expected behaviour:
Units should NEVER forget their orders and should keep trying to complete them even if they are stuck and they should always fire when within range of the enemy and their unit states allow them to do so.
This issue is really frustrating as I encounter this frequently in skirmish and multiplayer games with or without AI and really breaks the game.
duplicated with the following units:
cloakbot - sling
cloakbot - glaive
rover - fencer
hovercraft - lance (i think these just forgot their orders too)
and likely all the rest as well under different situations.
