I have to agree and I believe that this is something inherent to the sim or to the combination of the add-ones. Wrong NAVAID in the NavDataBase could be a trigger also or incorrect AI placement between AI sectors. The only way to test is to have a naked default P3D and fly transatlantic constantly adding add-ones progressively. Unfortunately, this method is extremely time-consuming.
Here is my solution for transatlantics that has worked so far for all my instances (PDMG, both 777 and 747) and I have never had this error since them.
1. Once you're at your initial FL, kill GSX completely.
2. As soon as you leave Shanwick ARTCC fire up X16 (anyway, it's absolutely nothing to do while you're over the pond) and go back to normal once you enter Boston ARTCC. That's all, even thought VATSIM folks won't like my approach, I know that.
3. At the TOD, reactivate GSX
Also, since I'm able to avoid this error while using X16 acceleration I have my own theory that incorrect AI placement between in-sim AI zones could play it's role. In case you're unaware, once you hit anything faster than x8 acceleration, P3D internal engine suppresses any AI activity. Hence, those of you who fly in a normal time tend to face an error with greater probability.