The phrase "again the problem of" is correct and usable in written English.
It can be used when revisiting or reiterating a previously mentioned issue or challenge.
Example: "In our discussion today, we must address again the problem of resource allocation within the team."
Alternatives: "once more the issue of" or "revisiting the challenge of".
Once again the problem of how to compensate slave owners for the loss of their property stood in the way of abolition.
To see how efficiently it works, consider once again the problem of gambler's ruin and let N be the first value of n such that Sn = 0 or m; i.e., N denotes the random time at which ruin first occurs and the game ends.
Again, the problem of incentives was not treated in his paper.
In this article we raise again the problem of lack of a mechanical ventilation system in all Romanian schools.
Note that we have to face again the problem of evaluating the expected value of a fraction.
It turns out that a linearization of the lens rigidity problem is again the problem of s-injectivity of the ray transform I.
Again, the problem on Facebook is one of personalization.
Like many long-time readers of "Pride and Prejudice," I've returned, again and again, to the problem of Charlotte Lucas.
They all do, however, share a decidedly Western orientation in style, outlook, methodology, and more; seldom are things viewed from the Chinese perspective, and consequently charges of a Eurocentric bias in Chinese philosophy as a field of study are unfortunately not without merit, increasing yet again the problems of interpreting them appropriately.
But his finest work (thus far, anyway) was written early — which returns us again to the problem of a poetic "career".
Shaw again addressed the problem of how to resolve his play when he agreed to write a film script based on it for Gabriel Pascal.
