This item has been identified as an outstanding known issue. A workaround has been provided until the issue is officially fixed.
Issue
You receive an error when attempting to sync if you have changed the Format of a Line Item to Number and enabled Breakback on that same Line Item, within the same revision.
Error
An internal error occurred while preparing the structural changes for synchronization. Reason for error: Line item M.a does not currently support break-back
Workaround
To workaround this, disable breakback for the Line Item referenced in the error , sync to your production model, enable breakback for the same Line Item, sync to your production model.
If this workaround is not suitable in your use case, please contact Support at support@anaplan.com.
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Internal Reference: ALM-1454
