Running count with a filter

Hi all, 

Not sure if this is because it's a New Year and my brain has yet to accept it, or if it's actually something that's going to be difficult! 

I have the following:

RunningTot = 
CALCULATE(
    DISTINCTCOUNT('Location'[ID]),
    FILTER(
        ALLSELECTED('Location'[ID]),
        ISONORAFTER('Location'[ID], MIN('Location'[ID]), ASC)
    )
)

Works perfectly, counts the staff, tells me how many they are in each location

However, I now want to add in an additional complication.

On this table there is also a location field - which varies between office, field, home-based, flexible - and allows for multiple ticks for each staff member (as it's where they are willing to be). What I want to do is break down my above count, so that it only counts those that are ticked as 'flexible' but then reports back on the other locations as well. So, outcomes being out of everyone that is 'flexible' - 9 are home-based too, 14 are field, 2 are office - duplication of counts doesn't matter in this instance. 

I can't use a filter in the report as if I tick flexible, it will just show those that are ticked as that and disregard the other locations (which is what I want to report back on).

Hopefully this makes sense

Thanks for any guidance