Diagnosis
Continuous writing and rewriting to a microSD card (especially one that isn't high-endurance) will eventually cause it to wear out and develop errors, leading to corrupted video files.
How to Fix It
The first step is to format the card within the camera's system. This clears the file structure in a way the camera understands. In the Lorex app, go to your camera's settings, find "Storage" or "SD Card," and select "Format." This will erase everything on the card, but it's necessary. Use this as a chance to replace it with a card rated for "High Endurance" or "Continuous Recording," ideally Class 10 or U3, and no larger than 256GB (which is the max most Lorex cameras support).
If That Didn't Work
The SD card slot itself might have a poor connection. Power down the camera, remove the card, and carefully re-insert it, making sure it clicks fully into place. Also, check the card for physical damage or dirt on the metal contacts.
Heads Up
Never just pull the SD card out while the camera is powered on. Always use the "Safely Remove" option in the app settings first, or power the camera off, to prevent data corruption.