I truly apologize for resurrecting an old thread but I feel like this topic should be pinned. I would also like to give a HUGE thank you to Luxen for the loading freeze fix. I have been building a campaign for 2 months and it would have been all for nothing were it not for this instruction on how to fix it.

By checking the mods in the main menu and then saving the campaign to another save fixed the blank scenes and loading freeze bugs. Thank you so much again!