RGSS3 - Splendith Save + DataManager.save_game error

Script link: https://forums.rpgmakerweb.com/inde...d-engine-with-real-time-loading-screen.40096/
I'm using a completely non-edited version of the script above.

When using that script, the game has trouble fully saving until you go into the save menu, exit, and then force save again.
I have no clue how to approach fixing this. (The rest of the script works perfectly fine.)

I've attached a game demo below if you'd like to try this out for yourself. I added a script call that manually forces the save file to be deleted before forcing it to be re-saved to see if it was a matter of the save file being empty when force-saving, but it doesn't fix or change anything.