We are in 4.9.81 using regular (non-legacy tile) is it possible to search for null vs not null.
Search for records with both state and province columns are null
The setup for the String field can not be set to use drop-down search back.
TDM Portal 4.9.X
Component : CA Test Data Manager
So yes this is possible, with conditions.
1) numeric fields always come up with the drop-down button to show the option for IS NULL or IS NOT NULL.
2a) by default when you set up string fields these DEFAULT to having a drop-down list. When the drop-down list is enabled you must match an existing entry in the column and can not use IS NULL to IS NOT NULL.
2b) If you change it to not use a drop-down box then you will have the same option you have for a numeric field.
3) for date fields there was an issue with the IS NULL and NOT IS NULL working properly and this is fixed in build 4.9.211