Currently SUMMARIZECOLUMNS is not supported fully in a modified filter context. I find it a real pity as this is the only function that creates a table dynamically with only filter context and no row context (vs SUMMARIZE, ADDCOLUMNS, SELECTCOLUMNS). For instance, if we create a measure including SUMMARIZECOLUMNS and we use that measure under the effect of slicers, the engine throws the error: 'SummarizeColumns() and AddMissingItems() may not be used in this context.'
When will this be supported? It would certainly be a great addition.