Try this on a single switch first.
Go to the Master switch of the stack
Drill down to one of the linecard switches
Go to the manage page of that member switch
Import settings
If that performs the update properly as I'd expect, then you repeat the steps on the other switches in the stack or use the bulk method:
Go to the folder that has the switches (if you list all devices, then filter by type)
Click the modify devices wrench above the list view
Check the switches that need updating
Import settings