UPDATE - Related: For the "Connex cannot modify the grouped items on invoice" issue, the cause stemmed from an incomplete coding change that was published. At time of writing, the fix for it appears to have been published an hour ago. I would advise telling Customers to delete any affected Transactions from QuickBooks and resync them.
A patch to address this issue was deployed Friday morning, 10/23/2020, as of 9:00 AM EST. If issues persist beyond this point, please contact us. If you need to re-sync missed sales, please see:
QuickBooks Desktop, manual/historical Sync:
https://help.syncwithconnex.com/hc/en-us/articles/360045546012-How-do-I-manually-sync-sales-to-QuickBooks-Desktop-
QuickBooks Online, manual/historical Sync:
https://help.syncwithconnex.com/hc/en-us/articles/115003851203-How-do-I-manually-sync-sales-to-QuickBooks-Online-