Toddler bed transition issues...

I was wondering if anyone else is having this problem. My son is 23 months and we are trying to transition him from crib to toddler bed. He was climbing out of his crib and injuring himself so we had no choice but to move them to a toddler bed. He sleeps in his toddler bed no problem at night but will not sleep in it during his nap time. I’m not sure why he will not stay in his bed during naptime. I lock up all his toys, I have locks on all the drawers and the closet, I have blackout curtains in his room, I have a safety lock on the door on the inside...

Is anyone having this problem or has had this problem? If so, what are you doing or have done to get them to stay in bed during naptime?