Sorry, no it's not. I'd start with checking all your parameters and if it was in my tank I'd do water changes with water from a "healthy" established system to help get beneficial microbial stuff.
Put in super low flow, and feed, I've had fully receting torches reattach to the skeleton but takes time and nursing, meanwhile, check all parameters, rule out anything you can, (too high flow, ammonia spike, ect)
Also is it wild or aquacultured. Survival rate on wilds is much lower compared to something born and raised in a replicated environment. Best of luck! Post updates!
The other short tentacle is happy as can be I had very little flow before got the flow up a lil bit more now was told my a local here that it might be splitting?