File missing after restarting within 30 seconds of save/creation?

Hello- We can create a simple file (txt, img, etc.) in any location and open it, but if we restart (power cycle) the unit within 30 seconds, the file is either missing or is empty when everything comes back online. Is this something that is expected or is there a way we can manually “close” the file to make sure it doesn’t get removed if a user reboots the unit?

Thank you!

Linux is cashing files and disk access to increase performance and decrease a flash storage wearing.
So if you doing abrupt power cut, uncommitted cash data will be lost. You either need to do a graceful shutdown or use a sync command to flush cashed data.