Keeps crashing on iPhone 7 Plus

Ive been a Filmic Pro user for several years, dating back to my iPhone 4 and have always loved how great the product was. However, I tried using it on my iPhone 7 Plus with the DJI Osmo Mobile gimbal on Thanksgiving to capture some videos of my family (since the DJI app is not that great and Filmic Pro offers more control). Originally, I had the settings set to save video to the app; however, after I saved several of the videos to my camera roll and deleted them from the app, I switched the app to save files directly to my camera roll and then I tried recording a long video (>15 mins in 4K) of my father carving the turkey. It stopped recording after 15 minutes and the screen on my iPhone froze and I couldnt get out of the app without powering down the phone and restarting it. Once I did this, I found that the large video file did not save to the camera roll and when I tried to launch Filmic Pro, it would load a black screen with the logo, stall for about 10 seconds, and then crash and return to the iPhones main screen.

No matter how many times I try rebooting or restarting my iPhone, I cannot get the app to launch. I dont want to delete the app and reinstall because I think the video I took is still somewhere saved inside of it (when I checked the used storage for the app in the iPhones settings, it says 17.5 GB are already being used by the app and that is the only video that would be saved in there).

FilmicPro, please fix this!! Ive loved and used your product for years and I really dont want to lose this family memory that I know is somehow still saved on my device but stuck inside of the app that I cant open!! This is normally a 5-Star product but with this huge glitch, I cant give it that full rating.

crgunn49 about Filmic Pro－Video Camera, v5.5