NovaPlat

A number of passive abilities/beneficial "things" owned by some vehicles fail to work when the said vehicle is affected by iron curtain. These includes: 

1. Drakuv/Apocalypse infantry healing aura will disappear if it is casted with iron curtain, and lose it forever after the effect wears out.

2. Cyclops close-range firepower buff also fails. If it is ordered to fire at close range with the effect of iron curtain, it will only fire its main cannon and there are "hit" animatioin shown on the Cyclops. 

3. Bison/Mastodon/Leviathan: if you use iron curtain on them when the self-repair process is on, the animation continues but is unable to actually heal the vehicle. 

And I think I found reason to some of these. While Bison/Mastodon/Leviathan's situation is different (uses a particle system), the previous two are due to the attach effect. These functionalities use attach effect but doesn't have an AttachEffect.PenetratesIronCurtain=yes tag, therefore the effect does not work when the unit is affected by iron curtain.