To resolve the issue of blocks in Block Craft 3D only refilling while using the app, follow these steps:

1. Check App Settings: Start by checking the in-game settings. Open the Block Craft 3D app and navigate to the settings menu. Look for options related to resource management or automatic refilling.

2. Enable Background Activity: Ensure that the app is permitted to run in the background. This can sometimes be controlled via your device settings. Go to your Mac's System Preferences, select "Energy Saver," and ensure that any settings that might hinder background processes for applications are adjusted accordingly.

3. Restart the App: Sometimes, simply restarting the app can fix issues like these. Close Block Craft 3D completely (make sure it's not running in the background) and then reopen it.

4. Update the App: Make sure you have the latest version of Block Craft 3D installed. Check the Mac App Store for any available updates. Updating can often resolve bugs related to performance, including background activity features.

5. Reinstall the App: If the problem persists, consider uninstalling and then reinstalling Block Craft 3D. This can resolve any corrupted files or settings that may be affecting how the app functions.

6. Look for Community Solutions: Check forums such as Reddit to see if other users have encountered similar issues. They sometimes provide solutions based on community experience - learn more - learn more.

7. Contact Support: If none of the above steps work, it may be helpful to reach out to the Block Craft 3D support team for assistance. They can provide specific guidance tailored to your issue.

By following these steps, you should be able to restore the automatic refilling feature for blocks in Block Craft 3D while the app is in the background.