Problem with Lost Photos XT4

[Zofo58]

I am new to the Fujifilm system and recently bought a used XT4. I switched my two Lexar 256gb 1667x xc2 from my Olympus to my XT4.  After a few uses I got the message to switch the camera off to reset (not sure if that is the correct wording of the message).  That worked out ok.  This weekend I had taken hundreds of shots and changed lens near the end of the day and got the message again.  I switched it on and off and took a few more shots. When I got home I only had the shots from after I changed lens.

I am confused if it is a sd card problem with compatibility or if it is a more serious problem with the camera.  I did notice that when I deleted the photos from the card rather than format it I did not have this problem or maybe that was a coincidence.  I would appreciate any wisdom on this, thanks.

[Zofo58]

I have since purchased the compatible SD cards and everything is working just fine.

[Giampaolo Masserano]

It is mandatory that every memory card (new or old) MUST be formatted when it is inserted into a camera.

Simply moving it from one camera to another is not enough because there are dozens of EXIF data and hidden codes that can conflict with cameras from different brands.

[Zofo58]

Thank you for your response. I didn't know that.