Hello I have recently started to use a dji mini 4 pro drone in the lab where I work that previously worked (when someone else used it). I flew a small test flight today and I cannot find the flight log. It's not recorded on the controller or on the micro sd card.

I attach an image showing there is no flight log in the micro sd card which I put in the controller.

Which controller are you using, RC2 (built-in screen), or the RC-N2 (attach your phone)?

If its the RC2, logs are stored on the controller itself, not the SD card. You'll find the logs in the folder:
DJI RC2 › Internal shared storage › Android › data › dji.go.5 › files › FlightRecord

Flight logs will be in the TXT format.

Hi edwinmeriaux, thank you for reaching out. Kindly check the remote controller internal storage as advised above if you're using RC2. If the issue still persists, kindly share us the following details and we will forwrad it to our engineering team for further check :

1. Mobile device and system version
2. App version
3. Export the Flight record and tell us what time would the lost data have been generated.
4. App Log

Thank you for your understanding!