Cannot save a short video from Boomerang app to Photos (PHPhotosError- Domain error -1.)

I just got this issue recently this morning. I record a short video with Boomerang app, but couldn't save it. There's always an error pop-up as per the below photo.

I already tried to remove the app, then reinstall it. But the issue is still not fixed. If anyone have a solution for this issue, kindly advise me. Thank you!!

P/S: I am using the iPhone 11 Pro, iOS 14.4