It appears that there is a new maximum range for missiles limit in 6.4-6.42 due to the new intercept course calculations. I just had this situation:
After firing those torpedoes, I would get many many error messages that pointed out a overflow problem with missile intercept calculation.(missed the opportunity for screenshot here) The number of error windows depended on how big the progression interval was. 5 seconds were like a couple dozen; 30 seconds never seemed to end (thought it hanged up for quite a while). If I had to guess I would say it popped seconds*missileCount error windows, so 40 first, then 240 later - or something not directly depended on seconds, but still indirectly to time and minimum calculation interval. I guess this because after forwarding for an hour, it was still not more than the 30 seconds.
Now the missiles have passed a certain point though, and I can progress without error windows again. Thus there must be a maximum distance before bug out, and I will be damned: it seems, again, to be the 2.147 billion... . In suspicion of that, I checked the distance to the target when the errors came up, and it was something like 2.2b. Since I tested the torpedoes at closer range successfully already, I had enough hope to push through another couple hundred error windows in an hour calculation so that maybe, after this line, the problem would vanish. And it did.
...This 2^31 is my first numerical enemy by now. Seems like I will be hating it on a couple of other occasions in Aurora future.