After renaming my RasPlex device it still shows as RasPlex inside my Android app.

Can this be changed or fixed? Otherwise if I have multiple RasPlex installations in the same general area all will be named RasPlex.
Besides, can anyone confirm this?

i.e. my PMS shows with the custom device name I gave it.

You have to change it in two places if you want it show correctly everywhere.

System Settings > System > System Name
-AND-
Preferences > Gear > Services > Device Name