When the sync is stalling at 5% like that, it typically means that the communication between your devices is failing. So you shouldn’t need to do anything with your Sync Keys or Shards directory.
A few of the things that would be good to confirm are:
- Are your devices on the same WiFI network?
- Are you leaving Codebook for macOS open and unlocked during the process and is it set to Desktop WiFi sync under Codebook menu > Preferences > Sync Tab?
- On your iPhone, have you allowed Codebook for Local Network privacy? This setting can be found under iOS Settings > Privacy > Local Network and ensure that the switch next to Codebook is switched on.
- Try re-selecting your computer name under within the Local Network browser within Codebook. This can be found at Sync View > Computer Row within Codebook (even if your cached computer name is showing up on that row, select the row and see if your computer name shows up within the Local Network screen and re-select it).
These suggestions, along with a few others are on our Troubleshooting WiFi sync help page here: Codebook Help - Troubleshooting WiFi Sync
Please let me know if these suggestions are helpful. Thanks!