The plugins when attached as a 'sheet' (preferences, use dialog for effects set to false) doesn't work properly, as there is a single instance of the plugin for the application - so if you use the effect in another window the data references are corrupted.
The easiest solution may be to remove this option and always open in a dialog.
fixed in 2.5.8 by creating a new PluginClass instance for each document as needed. Application starts faster as well, since 'init' phase is performed on-demand
The plugins when attached as a 'sheet' (preferences, use dialog for effects set to false) doesn't work properly, as there is a single instance of the plugin for the application - so if you use the effect in another window the data references are corrupted.
The easiest solution may be to remove this option and always open in a dialog.