When executing Maintenance WO, It shows operation is "Not available for assignment"

Summary: When we're executing a maintenance work order on the Redwood UI page of "My Maintenance Work". After issuing material and reporting resources, on the operations page it shows that this particular operation is "Not available for assignment" and because of that, we're not able to complete the work order. Please guide us in resolving this issue and proceeding with WO execution.

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