Blackboard variables with default values are not set if a material is already created even if that variable was never included in the initial setup of the material
# Create a new shader graph (any type)
# Create a material using this new shader
# Add a new blackboard variable to the shader: blackboard => '+' => any type
# Set the default value. Select the new blackboard var => Graph Inspector => Default
# Select the material created in step 2

Expected result: The default value is applied to the existing material

Actual result: The new value is set to the type's default value- integers 0, colors white, e.t.c

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