Hi, first thought is… are you sure you actually made a copy.
Then, confirm how you are mounting the disk as this can be done by label or uuid.
When you add disks they end up assigned with an available identifier like /dev/sdb
Which will change for each new thing plugged in and removed.
So, that could be the issue right there.
Easiest solution is to use the tool fstab to make sure you mount the disk by either label or uuid.
uuid is the way to go because it is a unique sequence that confirms exactly which disk you are uniquely using. You can write an fstab rule for each SD card to make sure they are mounted properly. See: