AI ignoring ZOC rules? Or weather shenanigans?

[SSLConf_pewp3w]

I am playing through US Corps right now and at multiple points enemy units have moved to attack my Artillery units although they had no way to see them if they follow the rules.
At first I thought that it might be a lucky move by the enemy, but while I can not rule it out it seems unlikely since they move in a way avoiding other units and stopping without running into an ambush.
The only way the AI could have seen my vulnerable unit is with a bunker that a sight range of 4. The unit has two tiles between the bunker at itself, so sight range of three would be needed. On my turn it is cloudy though, so the bunker should not be able to see me, or does the weather already change on the enemy turn when it gets clear again afterwards? Because this is not the behaviour when the player moves second

[Moniker]

I'm pretty sure cloudy weather affects visibility only in the sky and not on the ground. So the bunker with vision range of 3 or 4 could see your unit.