i clean regularly. and a tank can never be too big as long as there is proper foliage and hides. hes 2 1/2 ft but regardless they live in the wild and are fine
There can be a lot of reasons why a royal would stop hiding. the most common is a temp issue.
You need a warm hide that has 89-92ºF temps inside it (young snakes do not need as much heat as older ones) and a cool hide that inside it is 79-81ºF the one most over look is the ambient AIR temp not surface temps but the temps of the air inside the enclosure it needs to be at least 79 and up to 85 is fine.
I have mine set to ramp, I use 80/90 and the ambient at the coolest (around 5 am) is about 79-80ºF. By 7 am it is 81-2º and at the the hottest around 2 or 3 pm it is 84-5ºF.
Check your temps very carefully when a royal chooses something over security it is almost always a survival imperative.
The other idea is that where ever it is staying is a place where it cannot see out. Glass is funny like that sometimes it is as good as opaque. It is possible that it is unable to see out and is under something or has enough perceived cover to make it feel like it cannot be seen.