Can understand your concern
I know mine have given me the panics over the years.
Is there a noise that might get Licky home quickly like a treat box rattling or a fav toy.
Check all the usual places then widen the search.
This heat might have effected Licky and made him want an extra snooze.
I notice that Licky has a vets app and wondering if this was routine
Am sure we have all been in this position but just have a good search then you feel you are doing something