Different measures returning same value

Hi Agent47 -  It is returning the same value because the ALLEXCEPT function might not be filtering the way you expect, likely due to the relationships in your data model.

create measure RA_SUM as below:

Measure_RA_SUM =
CALCULATE(
DISTINCTCOUNT('Risk Assesment'[Ra_Code]),
TREATAS(VALUES('Hazard'[Risk]), 'Risk Assesment'[Risk])
)

another measure sum2 

Measure_RA_SUM2 =
CALCULATE(
DISTINCTCOUNT('Risk Assesment'[Ra_Code]),
TREATAS(VALUES('Consequences'[Control_Type]), 'Risk Assesment'[Control_Type])
)

sum3 measure:

Measure_RA_SUM3 =
CALCULATE(
DISTINCTCOUNT('Risk Assesment'[Ra_Code]),
REMOVEFILTERS('Risk Assesment'[RA_Type]),
REMOVEFILTERS('Risk Assesment'[Vessel]),
VALUES('Risk Assesment'[RA_Type]),
VALUES('Risk Assesment'[Vessel])
)

Measure_RA_Code_Cnt (No Change)

Measure_RA_Code_Cnt = DISTINCTCOUNT('Risk Assesment'[Ra_Code])

THorughly check that the relationships are correctly set up, and verify that Ra_Master_Id is properly connecting Hazard and Risk Assesment.

you can also use the Performance Analyzer or DAX Studio to see how filters are propagating across tables to understand any unexpected filtering.

Hope this helps.