Lxd import "please ensure that the containers storage volume is mounted" (but it is mounted)

Hi
I’m just trying to import some containers that I zfs sent across to a new host.
I’m doing the usual of mounting the new dataset in the correct location then running lxd import, but I’m getting a message saying the directory appears to be empty.
However the directory is not empty and containers what I expect (backup.yaml, metadata.yaml rootfs folder etc) all looks correct.
Could this be permissions related, I’m sure I’ve only started running into this recently.
Cheers,
Jon.

For the record, all zpool, dataset and storage pool names are the same from source to destination, same version of ubuntu, same lxd 3.18.

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OK, I just rebooted the server and tried again and it imported it this time around. Very strange!!!