Binding property of a REF in UMG not working

Hello. I’ve a UMG which gets a REF to my Gameinstance on Construct. I bind a property (bool - button is enabled) to a pure function which resists inside of my Gameinstance. The button is not enabled.
If I create a Bind function inside my UMG which does nothing than returning exactly this function from my gameinstance it is ok.
If I use the setup in Screenshot “NOK” - watch the checkbox in front of the setting - it disappears. Bug or Feature?
Some screenshots:

121711-nok.png

121713-ok1.png

121714-ok2.png

anything I can provide to help somebody clearing this up? Or am I the only one running into this bug?

don’t get it in 4.15 - seems to be solved