In Select Mode (blue cursor), holding the L and R buttons simultaneously will open the inventory. If this fails, check the version of the program at the bottom left of the Information section to verify that it was updated correctly.
Appreciate the feedback. No current plans to add support for LGPE since they do not feature a traditional box storage system and use Generation 7 formats.
This program aims to minimize the probability of a game-breaking modification, so no current plans for such functionality. Regardless, appreciate the feedback.