I tested it out again and I didn't see any issues with at least this newer version of the plugin. If you are experiencing issues, please tell me how to reproduce them step-by-step. Thanks!
Viewing post in Potential Bug
I simply edited the already existing poison state by increasing the Ex Parameter Hp/Mp Regeneration (with a - in front so it takes hp/mp away instead of giving it.) When the plugin is on, not only do the states not work but they even remove themselves at the end of the Player's action even when it set it to only be removed by the end of battle.
To make sure it was the plugin I even turn it off for a while and attempted it a 2nd time and it worked as intended. Its only when the plugin is turned on do I have these issues.
I even redownloaded the plugin a 2nd time before commenting this to make sure it was up to date but the issue persists.
I'm using mostly Yanfly's plugins alongside this one. As well as a few from SumRndmDde and Hime plugins. Moving it to the very top broke a few things, so I try to keep it below the Yanfly battle Engine Plugin.
Its still not working on my end. I tried moving it to the top, bottom, or above and below certain plugins but the issue persists.
Did you set the Ex Perameters of Hp or Mp Regeneration to -X% to cause an inverse effect like I did or did you do something else?