Found what cause the troubles. Later will post additional file, a small js snippet that must be placed after OcRam's Core and before my Formation Manager.
As temporary solution, if possible, move my Formation Manager above Ocram's Core. That should work too, though I do not recomend it as permanent solution.
Ended up simply updating my plugin to not use for-in loop when iterating through array, since for-of was working just fine.
I think OcRam should update his core too, because it would conflict with all other plugins that use for-in loop for iterating through array, but that is up to him.
Downloading my newest version should resolve your issue. Would like to know if is so. Thanks!