Solution:
It turns out that the “Set Member” boxes are not working correctly or I am not using them correctly. I have them set with the Image pin checked for the SlateBrush, however, they’re not updating very well.
When I changed to the standard and bloated Get/Set Brush boxes, it works fine.
To me, it doesn’t make any sense why the “Set Members” boxes are failing. It might be a timing issue. But the old fashioned way works. Has anyone else experienced issues with these things?