Bug (?): Invisible enemy units

[GeneralYouKnowMe]

I played a battle where the enemy's units were invisible. Even when my units were 1 meter from them, they could not see the enemy troops. I get that you can hide, but come on. The only way to engage the enemy for me, was to literally run into them. That resulted in an immediate rout of my troops. The enemy units could even shoot at mine, without being discovered. You could see the soldiers for a couple of seconds (semi transparent) and then they would disappear. And I could not shoot back.

The map had rain / fog and also some good english troops, just FYI.

Best regards.