Distinct count while ignoring filter context

Your "Plans"  table is actually a "Plan Type IDs"  table.

Then you can use the table visual to show all the required data.

Hi flyinggnugget 

I’d like to acknowledge the valuable input provided by lbendlin . His idea was instrumental in guiding my approach. Please allow me to make some additions.

You can add the Plan Type Id in the Plans table to get the “Distinct Count of All Plan Type Id”.

If you want to use measure, you can try the following steps.

Change the cross-filter direction of the relationship to Both

Distinct Count of Plan Type Id = 
CALCULATE(
    DISTINCTCOUNT('Plan Type'[Plan Type Id]),
    FILTER(
        ALL('Plan Type'),
        RELATED(Plans[Plan Type Id]) = SELECTEDVALUE(Plans[Plan Type Id])
    ))

Distinct Count of All Plan Type Id = 
CALCULATE(
    DISTINCTCOUNT('Plan Type'[Plan Type Id]),
    FILTER(
        ALL('Plan Type'),
        RELATED(Plans[Plan]) = SELECTEDVALUE(Plans[Plan])
    ))

Result:

Best Regards,
Yulia Xu

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.