One thing to do is check the recordings section in the Video tab of your Alarm.com account for clips at the specific times you think a video should have been recorded. Its possible you didn’t get the notification but a clip was recorded.
If you find that motion recordings are not triggering when you want them to, disable the motion recording rule, wait 5 minutes, then recreate it. Wait an additional 5 minutes for the camera to get the new rule and test for functionality.
A guide on motion sensitivity settings and motion recording troubleshooting can be found here: