delete_all_material_expressions_in_function Doesn't delete all expressions in one go.

UDN: https://udn.unrealengine.com/s/case/500QP000009NxNBYA0/deleteallmaterialexpressionsinfunction-doesnt-delete-all-expressions-in-one-go?fromCase=1

A UDN user is reporting that the delete_all_material_expressions_in_function Python API does not delete all expressions in one go, but some expressions are left over. Calling the API repeatedly will eventually delete all nodes.

The user also found out that changing the delete_all_material_expressions_in_function implementation to iterate through the array of function expressions backwards solves the issue.

Evidence

• Flux [Link Removed] J-001: 2026-10-27 (engine 6.0.0-59684868), M_FX_ExitHologram had 218 expressions, 108 after delete_all_material_expressions; deleting each from get_material_expressions left 0 (rebuild 145).