Cell Format can be set to display NoData cells as dashes in Reports (PDF rendering) using this property: ReportNoDataNumberFormat = "- “.
Data Explorer cannot render dashes where there is NoData; this is how zero data cells are differentiated from NoData cells.
NOTE: This is an approved enhancement request and in the queue for a future release (TFS#5699).
Source: Office Hours 2020-08-13 Partner Enablement
