Two visual bugs happen frequently in multiplayer:

• Remnants that are in spirit form will often not appear transparent or any different from normal
• Remnants possessing entities aren't marked invisible and appear riding on/inside of the entity they possess

I've also spotted a third one, where my player was transparent as if he should be in spirit form, but while I was human. Is this one intentional?

Those bugs are theoretically fixed now, feel free to reopen if that's not the case