In reference to the question of whether or not Jump Point loops are forming in the current version, I can definitively say they are (at least in games that do NOT utilize Known Stars). That said, they are not forming at the proper rate (see below).
The test I conducted:
- Created a new game
- Deselected Known Stars (finally got the game to properly generate after the 3rd attempt, but that's a different bug...)
- Set Local System Generation % to 100 and Spread to 5
These settings should limit any given system to connecting to the 10 closest systems. As I was not using Known Stars, this is the 10 closest systems by System Number. To see what system numbers were generating I used no system naming theme, thus making it apparent which system numbers were generating.
In the attached image, System #1000 connected to System #2.
I suspected loops might be forming only when they had no other choice; for example, if all other systems within 5 had already been generated. As can be seen from the attached image, that is not, however, the case. Valid options for System #1000 to connect to should be Systems #0-4 and #995-999 (I'm fairly certain Sol is counted as System #0, though if that's the case it shouldn't have been able to generate System #995 given the range of System Spread of 5... honestly, I don't know what the hell is happening there). System #997 has not yet been generated, and would have been a valid choice.
I continued my exploration for a while past what's shown in the screenshot. And I've come to the inescapable conclusion that there IS something wrong with system generation / loop generation logic. The number of times an unexplored jump point had (for example) an 80% chance of connecting to an existing system and a 20% chance of connecting to a new system, and yet generated a new system defies random chance.
Time after time, no matter the odds against it, a new system was generated rather than a connection to an existing one.
I strongly suspect this problem began due to the "Avoidance of Closed Universe" changes in 2.1.1, as I haven't observed it previously.
Hopefully this is somewhat helpful.