I currently have the assignment to purchase a “SWIFT” From A. Liron. I have purchased the SWIFT and the task has not been marked completed.
I believe I triggered this by first purchasing the SWIFT and then getting the assignment a little later.
Can you please make a screenshot of the contract?
Here is a screenshot of the contract and the corresponding ship in my hangar. 
Ok thank you forwarded.
I have similar problem, I have assignment with federation to reach R4 but I have all R4 federation ships. I already had all the ships before taking the task.