Mine have always been very reclusive. Unless you have night lighting and watch the tank at night a lot. I keep on in my traveling tank and finally saw it again at a program after about 2 months of not seeing it.
They are really fun to watch if you can see it. In a large system you will never see it unless you get a super friendly, not shy one.
My traveling tank is 6g. I see it very rarely. However, my tank is also downstairs in the fish room and I do not stare at it much except when off on a program.