Update
Think I have resolved this for now.
I went back to our development server, updated the dimension with the latest master data refresh, updated all attributes, rebuilt all rollups, rebuilt all alternate hierarchies and verified structures.
I noticed that there were quite a few items not in the Default hierarchy but appearing in the Leave hierarchy. These "orphaned" items looked to be old members from testing, previous loads etc. It is possible that the members were removed from the Default hierarchy via a deletion from the dimension in Perspectives. (Still need to check if this causes the member to be deleted from the default but kept in Leaves).
I created some MDX to go through members in Leaves and not in the Default hierarchy, and delete them.
This cleaned up the orphaned/ unused members and the two hierarchies seem more aligned.
After a save data, I copied over the Product dimension and the hierarchies from the Product}hiers to Production.
So far so good - PAfE giving DIMIX values where alias is used, TM1Web returning reports with values, not just a blank structure.
Still not sure what happened here or how to prevent it from happening again but would be happy if anyone has anything to add.
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George Tonkin
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