ToME: the Tales of Maj'Eyal

I've had this happen on a number of characters and I can't figure out what is causing it. The location seems random. I'm not suffering a status-effect. The enemy doesn't appear to have gear that would cause it.

Just... every once in a while, a spell will just fizzle. That's the precise language. It doesn't happen on every character and it always seems to happen in battle.

What is causing it and what do I do about it? Any ideas?

Conveyance teleports have a 35% chance to "fizzle" if you do not have line of sight for the targeted tile. (vision range also matters)

Fizzle means, it will be a random teleport.

Aye, but that's not what's happening and it's been on a different range of characters, though all mages of some kind: Archmage, Necro, and Paradox. They've all suffered it.

There are some tiles where cannot be teleported.
E.g.: The Sher'Tul Fortress, the last level of the Hidden Compound, ...

Also Vaults, you cannot teleport into a vault tile, if you are not in that vault already.

Check always the targeted tile, where you would like to teleport.

All things I've tried...

Damn, I was hoping there'd be an obvious reason that I'd missed. Hmm...

Thanks.