I'll get right to the point:

Recently the flame forge and multiplayer flames have not been working, they are invisible. CTRL+L = No flame on me, Join a multiplayer game = Cannot see other person's flame if they have one.

Although, If I type /lp 0 hampa HIS flames are visible on my tori, So what's going on?

Are you using 3.88 or 3.9?

Also when you are trying to view the flame forge flame, try /opt particles 1.

Neither its 8.86

Guess I should get the latest :P

Edit: Although 8.88 has a lot of bugs and 8.9??

i am using 8.88 and it works fine maybe you should reinstall it

Well, 8.88 has a bug of gab and ungrab, when you have to grab and there is a joint at the back of the hand it will change the joint and not the hand.

Actually, the flame forge should work in 3.86. I'd recommend reinstalling, since I cant think of anything that would cause your problem.

Hmm, if it isn't already solved, try turning off any scripts that may be running, and also try turning off shaders. Hope it helps and good luck!