I'm new to this scene but I had the same issue. I know this is a really late reply but just in case anyone else couldn't get it working still. I'm currently trying my idea for a fix. I am moving the data for Pokémon Shield and other games onto my SD card rather than having them stored locally on my switch. This way checkpoint and my saves are in the same file storage location/device. You can do this by opening settings and then going to data management. The option move to SD card should be right there, once you select that, select the games you want to move and then start the transfer.
