IIRC, Pro Tools has a caching mechanism that basically stores the state of the plugin the very first time you load the plugin (via getStateInformation()) and then overwrites the default values via setStateInformation() the next times the plugin is loaded.
I don’t know if this is your case, but try to comment out the content of your setStateInformation implementation and see if it helps.
I’m not 100% sure, but if you remove the plugin, launch PT, then put the plugin back and re-launch PT, it should reset this cache.
Edit: here’s another thread about this: AAX / ProTools - plugin states persistent over multiple sessions?