As it stands now, CC-immunity/immovable pots and the 5 second buff from immovable(the heavy armor active skill) are 2 different buffs. This means that what immovable pots protect you from, 'immovable' may not.
Normally, I wouldn't care, but in vHoF, on the 4th boss, there are traps that take a long time to break free from. If you fall in one at an inopportune time, the long break free animation from them can result in an unavoidable death. Drinking an immovability potion can prevent the stun, but it only provides the unstoppable buff for 15.7 seconds with the alchemy passives, leaving 30 seconds where you have no potion available and have to wait 2 seconds while your character completes a long, clunky break free animation. (worth mentioning is that although the name of the buff from immovability pots and the phrasing used to describe the protections it provides are exactly the same as one of the morphs of immovable, they are not the same buff and do not provide the same protections)

If this can't be implemented, an explanation would be very appreciated.

I hope I'm tagging the right folks here to get this change in:
@Wrobel @ZOS_GinaBruno