Paul, do you mean that two and seven of the attribute LEVELS are non-significant without and with the interaction? That would be less concerning than entire attributes becoming non-significant, which would be odd.
Because the utilities of the levels are centered at zero, it's not a surprise that some of them have non-significant t-tests (which would change, by they way, under different kinds of coding) so that part really doesn't concern me.
The improvement in LL is pretty substantial, but of course I don't see how many d.f. you're adding with those interactions.