Data Management - Essbase Error(1260046) introduced on non-Gen1 Scenarios

Summary:

An issue appears to have been introduced into EPBCS last night which caused a lot of our Data Management Rules to fail (these have previously been running with no issues for 5 years).

The error message in each job log is : "Cannot perform cube view operation. Essbase Error(1260046): Unknown Member [Scenario].[Plan] used in query".

Content (required):

The equivalent rules for Actual Scenario continued to work fine (Actual is a Gen1 Scenario in our model, Plan has always been Gen2).

I found a workaround was to change the Scenario selection in each Plan Data Rule to the fully qualified name [Calculating_Scenario].[Plan].