There might be other plugin incompatibilities. Could you send me a list of stuff that's running on top of the proximity plugin? How big the the file you are playing (in kb)?Could you try setting up a new project with just this plugin and see if it works there?
I'm 99% sure its either a wrong setup or a plugin conflict.
if you take a look at this video, it works:
Those three plugins heavily influence the base mechanics of RPG Maker MZ, and are untested with this small plugin. Compatibility can't be guaranteed. I tested CGMZ core with this, works fine, but couldn't get the demo of MZ3D to run. A quick glance in the source code reveals heavy influence on the events...