LIVE: Transform Variable rotation not setting correctly

When trying to set the rotation value of a blueprint transform variable, changing the Y value will usually reset to 0 and change the value of X and Z as well.

1. Launch UE4 editor
2. Create a blueprint based on actor
3. Add a new variable and set type to Transform
4. Compile
5. Set Rotation value to : X=1.0, Z=1.0
6. Set Rotation value to: Y=128.0

Result:
X=-178.999985
Y=52.0
Z=-178.999985

Expected:
X=1.0
Y=128.0
Z=1.0