Paginated - Converting Null Parameter Values To Allow Multiple Selection

I have a report parameter that is populated by a query; however, at the source, it is optional and thus returns an amount of nulls. When allowing multiple values to be selected, the nulls disappear. Why Paginated Reports doesn't allow this is another question, SO I would like to convert nulls to "(Blank)" in my query to get around this but need help with the DAX syntax. Is this possible? The code is

EVALUATE SUMMARIZECOLUMNS('Projects'[SubDomain], FILTER(VALUES('Projects'[ProjectStatus]), ('Projects'[ProjectStatus] = "Active")), FILTER(VALUES('Projects'[WorkType]), ('Projects'[WorkType] = "Project")))
ORDER BY ('Projects'[SubDomain])