In my opinion, and it is only an opinion as I'm not a genetics expert, the ones that never stabilize may at least partly be due to partially dominant genes. What I'm calling partially dominant are the genes that if both of the genes at that gene pair are the partially dominant one you get one result. If only one of those genes at that gene pair is the partially dominant one you get a different result.
The best example I have is from chicken feather color genetics and the blue/black/splash gene. If both genes at that gene pair are this B/B/S gene you get a splash color. This is basically a white chicken but it has black splashed randomly in it's feathers. If only one of those genes at that gene pair is the B/B/S gene you get a blue chicken. It's actually more of a blue/grey but they call it blue. If none are the B/B/S gene you get black.
This gene also demonstrates where a gene has an effect only if another gene or condition is present. There are different ways to make black genetically so I can't just say a black gene. But the B/B/S gene only affects a feather that would be black if B/B/S were not present. B/B/S has no effect on a red or white feather.
I'm sure there are other reasons some beans never stabilize but I do think this can be part of the problem.
@Rhodie Ranch Russ typically starts his new bean thread early April. It should be starting up soon but he has a lot of organizing to get ready. So maybe another two weeks or so.
it took me a while to find it but at least i had fun reading about beans again. 
