Have you followed this step in order to locate Docker ressources on the SD card ?
If yes, there might be a problem with the SD card itself. Is it an industrial grade like WAGO SD card ?
Try formatting it first, in ext4 (explained in the procedure below).
Once it’s all set, I would recommand to reboot the PFC before doing the Docker container installation. Sometimes the SD card is not mounted properly directly after the change.
Also take a look to your container logs.