Re: Deployment of the new version of the Model - why error could be created? And how to fix it.
We faced this kind of situation once - Our case was deletion of few line items, of course before deletion we removed the dependency of these line items in all references. But somehow, while syncing Anaplan threw an error that the line item (which we already deleted) has invalid formula.
As a workaround:
We had to restore the DEV model to a point when QA was last synced - Deleted the formulas for line items which are not longer required - Synced to QA.
Restored DEV again to latest code - Sync to QA again. Since, this time QA doesn't have formulas for the line items to be deleted, the sync was successful.
If you are facing an issue on similar lines, this could help. Else, please share the exact issue that you are facing.