Unable to display parent-child heirarchy

I've often found errors reported from SSAS indicating a duplicate key value in the dimension. When I've reviewed the source data, the duplicates aren't found. While I can't shed light on why this error is popping up in the dimension, I can offer a solution that bypasses the error and allows the cube to finish deploying and processing.

If you open the dimension object and look at the properties, you'll see a section for ErrorConfiguration. If you change this to "custom", you can tell SSAS what to do when it encounters errors in processing the object. If you want to log the error and allow the processing to continue, use "ReportAndContinue" as the value for properties like KeyDuplicate, KeyNotFound, NullKeyConvertedToUnknown, NullKeyNotAllowed - whatever is appropriate for your design. I set the KeyErrorLimit to 1 and set the KeyErrorLimitAction to StopLogging so your log files don't get overloaded with the same or similar errors.

As I said, this doesn't SOLVE the issue, but it does allow the cube to continue processing and sometimes, I've found, that's enough.

Another option would be to use a union to get parallel periods for the current and previous member. Then extract the first item out of this, which will always be the current member (except in the case of Feb 29 where it should fall back to the previous member).

That is, effectively coalesce with the previous member parallel period as per below:

union 
(
    PARALLELPERIOD(
        [Date].[Fiscal Detail].[Fiscal Year],1,
        [Date].[Fiscal Detail].currentmember) 
    *(will be null if Feb 29)*
    ,
    PARALLELPERIOD(
        [Date].[Fiscal Detail].[Fiscal Year],1,
        [Date].[Fiscal Detail].currentmember.lag(1))  
    *(will be the prior year Feb 28 when above is Feb 29 )*    
).item(0)  *(get the first member out of the union set)*