Zofo58

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

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

I've had problems with the same Lexar SD card and having checked on the Fujifilm website it is not listed as compatible. https://fujifilm-x.com/en-ie/support/compatibility/cameras/x-t4/ I have ordered compatible sd cards and hopefully that will work.

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.