Why won't my superworms pupate?

I read the post here in feeders about breeding superworms and looked up some videos on YouTube and it seems like superworms are fairly easy to breed.

On November 5th I received a batch of medium superworms from Mulberry farms and separated out my biggest into a few tackle boxes. I have about 90 set aside like this with no food or moisture in separate compartments. All the sources I've read online say it will take about two weeks for them to get to the pupa stage. However, of the 90 I set aside only about 12 have morphed into pupa. Some of the others have curled up into the pre-transformation state while I was at work this morning but most of them seem to be just hanging out in their cubicles or trying --unsuccessfully-- to escape. None of them appear to be dead, but I was just curious if anyone else has had this problem. Is there something else I should do? Is two weeks just the minimum time it takes to start transformation?

Also, there seemed to be mixed opinions on when to shift them back into a community. Can I scoop the pupa out now and place them where they'll be as beetles or will hungry newly transformed beetles eat the pupa that haven't morphed yet?

Mediums may be too young to want to pupate - have any of the others you've still been feeding grown larger? I might try with the biggest of the larvae.

Somewhere I saw that they needed to be around two inches long. The worms I picked were around that length. Some of the ones I have left from that batch may be longer now. If these don't start pupating soon, I'll try swapping them out. Thanks!