The phrase "again the cause of" is correct and usable in written English.
It can be used when referring to a repeated reason or factor that leads to a particular outcome or situation.
Example: "The heavy rains were again the cause of the flooding in the area."
Alternatives: "once more the reason for" or "repeatedly the source of".
Once again, the cause of the tears is division.
Again, the cause of death was ruled unsuspicious; widespread news reports called it a suicide.
Again, the cause of this is unknown but we also guess that it was due to timing errors.
Blackwater's private army was again the cause of a major stand-off between US and Iraqi troops last December when one of its soldiers shot dead an Iraqi security officer in Baghdad.
Extra carrier detections are again the cause of the difference in performance.
Love was again the cause of another suicide attempt back in 2000.
We must, and we shall, set the tide running again in the cause of freedom.
These days, the Obama political team has the edge, again in the cause of emphasizing deficit reduction and with an assist from Congressional Democrats nervous about the midterm elections.
Recently, we have seen another definitive biography: The Secret Life of Marilyn Monroe by J Randy Taraborrelli, as well as in September The Final Years of Marilyn Monroe by Keith Badman which picks, yet again, over the cause of her death.
Officials at the Federal Aviation Administration have said they will not allow the planes to fly again until the cause of the safety problems is clear and fixes have been identified.
If so, the shutdown might once again advance the cause of third parties (of which Minnesota has a rich history), though none looks exactly well organised at the moment.As for the Democrats and Republicans, some optimists claim the cathartic shock will persuade both sides to stop pandering to their bases and find ways to solve the state's problems.
