If you want to find the maximum phase, you'd make another max summary field based on the max date summary field. See configuration for new summary field below.
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Field to summarize: Choose a field from the "table name" table -
[Phase] << field to summarize
Where the following is true:
[Date Field] = the value in the field [Max Date Field] <your max date summary field.
Function: Maximum
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See how that works for you.
