How to correctly use nested inheritance in UMG?

Layer 0.

  1. Create a UserWidget, let’s call it SizedWidget
  2. Inside SizedWidget, create a NamedSlot, let’s call it RootSlot

Layer 1.
3. Create a SizedWidget, let’s call it ButtonWidget
4. Inside the RootSlot of ButtonWidget, drag in a new NamedSlot, let’s call it ButtonSlot

Layer 2.
5. Create a ButtonWidget, let’s call it TextButtonWidget
6. Inside the ButtonSlot of TextButtonWidget, drag in a new TextBlock
7. Provide variable for TextBlock
8. Call variable into Graph

  1. Run application

Observed behavior:

Blueprint Runtime Error: "Accessed None trying to read property TextBlock_74".
Node:  Set Visibility
Graph:  EventGraph
Function:  Execute Ubergraph WBP Test Layer 2
Blueprint:  WBP_Test_Layer2

How to correctly use nested inheritance in UMG?