I've done a ton of testing, and found several culprits. One issue is a plugin, but the other two are caused by setting variables to specific game data.

One is the plugin "DK_Game Time". It has the ability to set switches in its parameters which it checks to turn on/off based on the time. If any switch is added to its parameters, your plugin stops working

Another issue seems to be with a parallel common event I have, which sets a variable to the player's "step" game data, then loops to check a second variable against the player's "step" game data until it matches. For some reason, checking a variable against the step data resets the icon (makes it go away and pop up again), so with this event running, the icon refreshes every 16 frames when the event loops and checks the step data again.

The last issue is with a simple plugin that I run to set some variables to the mouse X and Y coordinates whenever the mouse is moved (so I can run other events that check if the mouse moved). Running this plugin causes the icons to refresh just like the above issue every time the mouse moves and the variables are updated;

To make it easier to test, I put together a test copy of my project that has all of these bugs in it: https://drive.google.com/file/d/1LBqyqTatbJ_bsF-eynDVZmF8Uy6Zi0XI/view?usp=shari...

They are all disabled by default, but if you enable switch 10 , it will activate the parallel event that causes the 2nd issue. It also has the 2 plugins that cause problems, which are disabled by default. Enabling either of them will cause their bugs to happen.