Numbers not matching

Think I just got closer.  I think the random months working was due to it not knowing which months / year were greater than Jan 2025.  So i did the same but matched on a yearmonth formula column and now all looks good apart from Jan bizarely:

Forecast MRR = 
VAR BaseTable = SUMMARIZE( 'GBP', 'Dates2'[Month Year], 'GBP'[Source], 'GBP'[Rate] )
VAR ConvertedValueGBP = SUMX(
	BaseTable,
	VAR MaxDate = IF(MAX('Dates2'[Month Year Formula]) >= "202501", DATE(2025,1,31), CALCULATE( MAX( 'Dates2'[Date] ) ))
    VAR MaxDateStart = CALCULATE( MAX( 'Dates2'[Date] ) )
	VAR Source = 'GBP'[Source]
	VAR Result = CALCULATE(
		SUM( Combined[MRR] ),
		Combined[End Date] > MaxDate, 
        Combined[Start Date] <= MaxDateStart,
        Combined[PON or Not] IN { "PON", "Excluded" },
		Combined[Currency] = Source
	) * 'GBP'[Rate]
	RETURN Result
)
VAR BaseTable2 = SUMMARIZE( 'EUR', 'Dates2'[Month Year], 'EUR'[Source], 'EUR'[Rate] )
VAR ConvertedValueEUR = SUMX(
	BaseTable2,
	VAR MaxDate = IF(MAX('Dates2'[Month Year Formula]) >= "202501", DATE(2025,1,31), CALCULATE( MAX( 'Dates2'[Date] ) ))
    VAR MaxDateStart = CALCULATE( MAX( 'Dates2'[Date] ) )
	VAR Source = 'EUR'[Source]
	VAR Result = CALCULATE(
		SUM( Combined[MRR]),
		Combined[End Date] > MaxDate,
        Combined[Start Date] <= MaxDateStart,
        Combined[PON or Not] IN { "PON", "Excluded" },
		Combined[Currency] = Source
	) * 'EUR'[Rate]
	RETURN Result
)
VAR UnconvertedValue = SUMX( VALUES( Dates2[Month Year] ),
	VAR MaxDate = IF(MAX('Dates2'[Month Year Formula]) >= "202501", DATE(2025,1,31), CALCULATE( MAX( 'Dates2'[Date] ) ))
    VAR MaxDateStart = CALCULATE( MAX( 'Dates2'[Date] ) )
	VAR Result = CALCULATE(
		SUM( Combined[MRR $] ),
		Combined[End Date] > MaxDate,
        Combined[Start Date] <= MaxDateStart,
        Combined[PON or Not] IN { "PON", "Excluded" },
		ISBLANK( Combined[Currency] ) 
	)
	RETURN Result
)
VAR Result = ConvertedValueGBP + UnconvertedValue + ConvertedValueEUR
RETURN Result