At the initial release of this game there was a bug that sometimes when one was incinerated in cyrodiil the character would respawn permanently invisible. Can still interact with NPCs, attack players in PVP, all the while permanently invisible. Put in ticket way back then, no response, left game as friends were increasingly playing other games.
I returned to the game a couple of days ago and character is still bugged from more than 1/2 a decade ago. Put in another ticket and got a canned 'remove your disguise, reset ui' response. Went ahead and got a disguise out of bank and put on/off, reloadui figuring perhaps that may be a way to clear bug. Also Ive attacked a guard to go through the killed / respawn in game to perhaps clear bug. Still bugged.
On login or respawn, character is incinerated to a pile of ash, and is then permanently invisible. Not viewable by player, by friends, in or out of group. Character is not drawing in game.
If I had to guess there was probably a fix to the incinerate / player respawn put in place more than a 1/2 decade ago however I was no longer playing and perhaps the character was in some archived state and missed the fix.