I can guess what happened. Maybe not exactly WHY it happened, but what the immediate cause is. Try the update.
I'm not sure why it wouldn't be able to use the Party Limit Gauge - I've heard of others using it - so long as the plugins are in the correct order: everything that modifies skill cost should be above this plugin. But then, I also haven't really tested with it much. (There would be a valid reason why it would not be compatible with multiple party members spending Party Limit in the same dualtech - I have warnings against that very thing! - but one party member spending it should work fine. Also, do remember: the dualtech costs the skill cost of the component techs, not the dualtech itself!)