Mass Entity Config not displaying or accepting drag and dropped State Tree assets

This is not a regression. Tested in //UE5/Release-5.0 CL20979098

Mass Entity Config not displaying or accepting drag and dropped State Tree assets. The only clear way to assign a State Tree is by creating a State Tree from the drop down options, which will also no visible if you clear the assignment.

1. Create or open any project
2. Enable Mass Entity plugin then restart the project
3. Right click in the Content Browser select A.I. > State Tree
4. In the dialog box search for and select Mass Behavior
5. Compile, save, and close the asset
6. Create a new Data Asset derived from the Mass Entity Config Asset:
   • Right click in the Content Browser select Misc. > Data Asset
   • In the dialog box search for and select Mass Entity Config Asset
7. Open the asset then add an element to the Trait array
8. Select the drop down then search for and select State Tree
9. Expand the element then select the State Tree drop down

Expected Results:
Previous created State Trees are visible and can be selected. Dragging and dropping a State Tree would work or more information about why it can't be used.

Actual Results:
Previous State Tress are not listened, drag and drop turns it red but no other information is given.

UE-170920 still exists in 5.1.1?