Ideas
I just experienced this bug. I'm not sure at what point during the sleepover that it began because a couple of sims in my household successfully went to sleep in bed a bit earlier in the event, but the others were not able to do so by the time they were ready to go to bed. It isn't sim specific because I woke up one of the sims who was sleeping and he was not able to go back to sleep. My servo was not able to recharge using a bed either, but he was able to do it by clicking on him. My toddlers were also affected. The sleepover guests were able to go to sleep in their sleeping bags, but the sleepover participants all kept t-posing and resetting every so often, so they didn't sleep the whole night. I had my child sim try going to bed by using "place tooth under pillow and sleep" because that was available, but she immediately reset and no longer has the tooth. Going to manage worlds and then back into the household once the sleepover was over fixed it. Playing on PC with no mods or CC ever in this save.