It looks like this may be missing a MessageContract. This easiest way to solve this is to add a name to the request argument of the OperationContract.

Here's an update to your example:

[<ServiceContract(Namespace="tfcinc.com/listmanagement")>]
[<DeliveryRequirements(QueuedDeliveryRequirements=QueuedDeliveryRequirementsMode.Required)>]
type IListService = interface
[<OperationContract(IsOneWay=true)>]
[<TransactionFlow(TransactionFlowOption.Allowed)>]
abstract member SaveData: someValue:string -> unit
end

The addition of "someValue:" should allow this to work for you. Of course, this still doesn't explain the disassemble/reassemble fix.