hey,
i was playing with 3dsmax background and i have this problem, 3dsmax doesn’t show map in viewport…
(look at printscreen)
this problem is so dumb, i cant find answer in google.. anybody encounter that problem?
Try to turn exposure control off - it has no use in Corona anyway.
nothing changes 
It could be lost bitmap path or some problem with graphic driver. Try to switch from nitrous to directx and back again.
Does ANY bitmap/map work for you as bg? Have you tried removing the Ł from file name?
thanks, changing drivers, back and forward worked out.