According to your description, It sounds like you want to apply multiple aggregates on measure calculation, right?
IF that is the case, I'd like to suggest you add a variable with summarize function to apply the first aggregation, then you can use iterator functions to invoke the above variable table to calculate the second aggregate.
Measure Totals, The Final Word
VAR summary =
SUMMARIZE ( Table, [category 1], [category 2], "AVG", AVERAGE ( Table[Amount] ) )
SUMX ( summary, [AVG] )
Community Support Team _ Xiaoxin
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