Quick answer: Unity Shader Graph sub-graph property not appearing on the consumer material? Sub-graph properties must be exposed via the blackboard; default-exposed isn't automatic.
Sub-graph has a 'Tint' property. Master graph uses the sub-graph; material inspector lacks the Tint slot.
Expose the property
Sub-graph blackboard > right-click property > Exposed. Re-import. Master graph inherits the slot.
Or pass via Output
For per-instance values, expose via the sub-graph's Output node. Master graph wires explicitly.
Verify in master's blackboard
After sub-graph re-import, the property appears as importable on master. If not, the exposure didn't apply.
“Sub-graph properties are private by default. Exposure is opt-in.”
Establish a convention for sub-graphs: any value the consumer should tune is exposed. Document; reuse.