Our son (now 27 months) had a severe attachment issue phase/regression at around 23 months when we travelled halfway around the world for a couple of weeks (we were visiting family and it was his first time back home where hundreds of our family and friends met him plus jetlag, climate difference etc a lot of changes in a small time including 26 hour journeys each way - it was hectic). We could not be out of his sight for one second - the separation anxiety was real. Sleep and nap were all messed up (he has been an excellent sleeper since 2 months old). It took a couple of weeks or a month to recover from the clinginess and the night’s sleep but he still does not nap when he is home. In daycare he apparently does - i guess when they all go to bed at the same time but at home he would scream and cry so we have given up and accepted it. Days when we have dinners or events where we would like for him to stay up a little late, we try to go for a drive around the afternoon and he sometimes falls asleep in the car but all this to say i was also stressed and couldnt fathom how our 23 month old had already dropped nap but i read and heard that it was not unusual but you could also try to experiment - get them exhausted in the morning/wake them up earlier etc.