That's the spirit in which I offered suggestions- just bouncing ideas. For sure listen to those who breed BPs. If your snake is just "being weird" I sure wish she'd say so, & clear this up.
Nest box: I'd use whatever your snake laid her eggs in the time before- I'm assuming you provided a nest box of some kind? For my rat snakes, I provide a large tub (opaque) with very damp moss in it, & privacy around that (either inside or outside their tank). So they aren't able to easily see me walking by- like a towel over that end of their tank, or pieces of cardboard to block their view- whatever is easiest. Their tanks are already in a quiet bedroom, btw. Colubrids are variable as far as doing second clutches. My house seems to be under a "fertility cloud" as far as my snakes are concerned- in the past, I've had a rosy boa reproduce (they have "live" neonates, not eggs) by parthenogenesis too..."lucky me".That's why I suggested keeping an open mind- strange things happen sometimes.
If your snake isn't doing a second clutch but actually has one or more retained eggs, bear in mind that duds are often smaller & softer than good eggs- that makes them much harder for a tired female to push them out, & harder for you to notice them by palpation. So a scan is truly a good idea at this point, so you know for sure. And if she did retain eggs, the intervention is usually more successful sooner rather than later. I hope you get her figured out.