  We probe photo-induced loss for chemically stable bosonic $^{23}$Na$^{87}$Rb
and $^{23}$Na$^{39}$K molecules in chopped optical dipole traps where the
molecules spend a significant time in the dark. We expect the effective
two-body decay to be largely suppressed in chopped traps due to the small
expected complex lifetimes of about $13\mu$s and $6\mu$s for $^{23}$Na$^{87}$Rb
and $^{23}$Na$^{39}$K respectively. However, instead we do observe
near-universal loss even at the lowest chopping frequencies we can probe. Our
data thus either suggest a so far unknown loss mechanism or a drastic
underestimation of the complex lifetime by at least one to two orders of
magnitude.
