SYMPTOM:
In Strategy 9.x-10.x, when setting a value in "Null display settings" at the project level, the same value will be display for metrics and attributes when running reports or documents with null values.
CAUSE:
The behaviour is by design. The warehouse null display setting will take effect for both metrics and attributes.
ALTERNATE SOLUTION:
A user can use a threshold. He will need to define a threshold on the metric M1, define the condition for M1 is Null, then format it as replaced text "0.00".