Fetching Metadata-Updates on infuse 6.7 on iPhone is not stopping or infuse crashes / the iPhone-App is no longer syncing to iCloud

Yes and that’s the stand alone version of Infuse which 6.7 was the last update for the stand alone version.

If you want to continue using Infuse with the newer OS versions you’ll probably have to start one of the subscriptions to Infuse 7 Pro or use the free version of Infuse 7.

As long as you haven’t already take advantages of any of the bonuses offered to update to Infuse Pro 7 I believe you can still get one as detailed here.