change the opacity of an object will affect only a certain range from camera view and objects outside that range get hidden. it stays hidden, even if it comes back to camera view, until another change to the opacity is made.
found the bug on beta99
setup to test this bug:
load platformer example
change opacity of all blocks to 50 during runtime. then move right. the blocks outside a certain range are hidden and only reappear when opacity is changed again.