It would be really helpful if you’d provide the following information so our engineer colleagues can identify and solve your problem sooner.
Which device has the problem? Viewer or Camera - Viewer
Device Model Name: IPhone 7 Plus
OS Version: latest
Why do some of my recordings freeze after they have been tripped by the motion detector? A 30s recording may only have 10s of video before it freezes on a frame for the remainder? This only happens sometimes.