DAX measure not calculating correctly

I'm having an issue with a DAX formula in SSAS/Tabular.

I have a calculated measure (rtn_qty_adj) which provides the values as expected, however when I reference that formula in another calculated measure (rtn_qty_avg_adj), it gives incorrect values.
It appears that "rtn_qty_avg_adj" is ignoring or filtering-out the logic of the calculated measure "rtn_qty_adj".

Basically the dataset consists of returns quantities over a (monthly) timeframe.
Where there are big peaks/excursions in the data (ie; return qty. in a month is greater than uper control limit) , then in the measure  "rtn_qty_adj" I reset these peaks to the Average return qty.
So then I want to perform another averaging on the adjusted returns qtys. where the peaks are "smoothed-out" (ie; equated to the average)
Most of the calculations work just fine, except this one which is causing me a headache.

Appreciate all input/help!!

Formulae
Here's the formulae for the adjusted return qty and adjusted return qty. average

Rtn_qty_adj:=
VAR rtn_avg =
CALCULATE(
		(AVERAGEX(
			SUMMARIZE( drct_excg, dates[incr_base_date], "rtn_avg",  [Rtn_qty] )
		,[rtn_avg] ) )
, ALL(dates))
RETURN
IF( [Rtn_qty_ucl_1sd_otlr] = 1, 
	IF(COUNTROWS(VALUES(dates[incr_base_date])) >1,
		SUMX(VALUES(dates[incr_base_date]),
			IF( [Rtn_qty_ucl_1sd_otlr] = 1, rtn_avg , [Rtn_qty] )  )
	,
	rtn_avg
),
[Rtn_qty]
)

Rtn_qty_avg_adj:=
CALCULATE(
	AVERAGEX(
		SUMMARIZE( drct_excg, dates[incr_base_date] ,"rtn_avg", [Rtn_qty_adj] ) 
	, [rtn_avg]) ) 
, ALL(dates) ) 

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Fergal
DAX-issue.xlsx