Math Nodes are not updating on input

Add, Multiply, Subtract and Divide Nodes in the Material Editor are not longer updating on input but on the next node added to the Material.

Also Reproduced in Main Promotable-CL-2541904

[Link Removed]

1. Open QAGame Editor
2. Create a New Material
3. Add an Addition, Multiply, Subtract or Divide node
4. Add Two Scalar Values
5. Input one Scalar Value into the A input of Math Node
6. Input the other Scalar Value into the B input of the Math Node
7. Add any additional node to the Material graph

RESULTS: The Add (0,1) never changes until the new node is added

EXPECTED: The Add (0,1) loses the numbers as you input the values.

[Repro] [4.8] Material Graph Doesn't Refresh Inputs Until A New Node SI