Mr. Nilbog, found some potential evidence to this effect reading another bug report:
https://www.project1999.com/forums/s...ht=charm+invis
Basically there is a confusing patch message out of era stating:
Quote:
- Charm is immediately removed from charmed NPC's when the character
that charmed them casts invisibility
|
This may lead some to believe that invis wouldn't break charm, but this is incorrect. Somehow the 'Charm buff' remained on the NPC after charm breaking with invis, causing some problems such as being unable to re-charm the creature.
I am unsure exactly how 'see invis' works on charmed mobs, if you charm a mob I believe they will automatically face an invisible creature, regardless if you yourself have see invis up. So perhaps the 'charm buff' gives them a see invis ability, or perhaps it is inherited from their master?
Anyways, a bit of loose evidence but maybe something to go off. Wouldn't happen 100% of the time it sounds like, but could account for some of these charmed see invis creatures.
The eqclassic link in the bug thread mentions that the buff would remain to the 'max duration' of what the charm spell would last (It looks like that could be up to 20 minutes), but who knows exactly as your other links say it is a permanent 'see invis' effect and not something that will wear off.
On a side note, not sure if this random charm bug due to invis is something you would be interested in recreating, didn't do much hard searching on it, but would guess there is some evidence out there for it.