Get Display Names from another site list's multi person column

Hello

I am trying to get Display Names from another site list's multi-person column. 

I have Nintex Workflow where I use Query List with CAML query to get a list of supervisors and managers for a department. 

<Query>
<Lists>
<List ID="{23BC57C8-2E5C-462E-BFCE-EDFE10046D36}" />
</Lists>
<ViewFields>
<FieldRef Name="Manager_x0020_Person" />
<FieldRef Name="Supervisor_x0020_Person" />
</ViewFields>
<Where>
<Eq>
<FieldRef Name="Department" />
<Value Type="String">{ItemProperty:Department1}</Value>
</Eq>
</Where>
</Query>

I store the results in two separate variables, var_Supervisors and var_Managers (I tried a single line of text, multi and collection).

As expected the results are saved in format i:0#.w|<domain><username>;i:0#.w|<domain><username>.

I want to use the results in e-mail notification but instead of userIDs, I would like to have Display Names. 

I tried to use For Each action on the collection variable and Set Variable where I change the data type to Display Name, Semicolon delimited but with every possible variable type (SLOT, MLOT, Collection, POG) the workflow crashes with the error "Coercion Failed: Unable to transform the input lookup data into the requested type."

Any ideas on how this can be fixed?

Note: I did have Run if action to only run if the variable is not empty.