In a production list, I have added one new property to the list and updated an existing import action to import data into this property. This action remains unchanged otherwise. This change was made in the development model
In the production model, after the changes have been pushed from dev, and running the above action, the property mapped in dev shows as unmapped and does not update. Upon viewing the action in the prod model, the new mapping does not reflect in the action.
Do I need to make a manual mapping in the prod model as well? And will this affect future ALM syncs?
Check whether you have marked this particular import process is marked as Production data in dev model. If the import process is marked as Production data under Action settings-->Imports tab (in dev model) then the mappings will not be updated through sync to the deployed model.
Removing the process from production data followed by a sync should update your import mapping from Dev to deployed model automatically.
Also, with respect to future syncs, if the model is in Deployed mode, Anaplan will not allow you to do any action which will break the sync.