ArcPro adding a blank for No Null fields

[SuzanneBergman]

I created a table where two fields don't allow NULLS but when you add a feature to the layer it saves without a problem even with these fields not being filled out. It just automatically leaves it blank. When I share this table with ArcGISOnline it shows an * next to the two fields but again, when you add features without populating this field, it still allows it. Has anyone experienced this or can give me advice?

[Ed_]

@SuzanneBergman can you please elaborate a bit further by adding screenshots from Pro and AGOL and also what you intend is with the output on AGOL? Thank you!

[Bud]

1. What kind of geodatabase? If Enterprise, what vendor (Oracle, etc.)?
2. Is the fake null a space " " or an empty string?
   1. Related: 
      Documentation about empty strings, nulls, NaN, and Nil in ArcGIS
      Deleting a value in a FGDB FC Attribute Table: Why does the value get set to empty, instead of null?
3. Please provide a screenshot of the attribute table.