您需要将默认成员"添加到要忽略上下文的任何计算中.您的代码将是

You need to add "default member" to any calculation that you want to ignore the context. Your code will be

with 
member [Measures].[Turnover PrevYear] as 
IIF( IsEmpty([Measures].[Turnover Actual] ), 
    NULL,   
    SUM(      
       ([Store Status].[Store Status Type].defaultmember, ParallelPeriod( [Date].[Year - Quarter - Month - Date].[Year],1,[Date].[Year - Quarter - Month - Date].CurrentMember))
       ,   [Measures].[Turnover Actual]
       ) 
    )
Select  
non empty{[Measures].[Turnover Actual],[Measures].[Turnover PrevYear]} 
on Columns,
non empty{[Store].[Store].[Store].members}
on Rows
from [Sales Cube]
where (
[Date].[Year - Quarter - Month - Date].[Month].&[2020]&[1], 
[Store Status].[Store Status Type].&[Comparable], 
[Store].[Country].[Country].&[GERMANY]
)