Create new DAX calculation for denominator

Anonymous , if the date table is not joined then you can have two measures like

if date table is joined first measure will need crossfilter , in some case second might need that too

Case Managers =

VAR CaseManager = values('MHK Program'[Case Manager Name Care Plan])
VAR ReferralMonthStart = EOMONTH('Date'[Date],-1) + 1
VAR ReferralEndMonth = EOMONTH('Date'[Date],0)
VAR Program = values('MHK Program'[ProgramOriginal])
RETURN
CALCULATE (

DISTINCTCOUNT('MHK Program'[Program_No]),
FILTER (
'MHK Program',
'MHK Program'[Case Manager Name Care Plan] in CaseManager
&& 'MHK Program'[ProgramOriginal] in Program
&& 'MHK Program'[Enrolled] = 1
&& 'MHK Program'[Date_Received] >= ReferralMonthStart
&& 'MHK Program'[Date_Received] <= ReferralEndMonth

))

Case manager count

Countx( values('MHK Program'[Program_No]), if([Case Managers]>=1,CaseManager,BLANK()))

refer for crossfilter

https://community.powerbi.com/t5/Community-Blog/HR-Analytics-Active-Employee-Hire-and-Termination-trend/ba-p/882970