My experience is that it depends upon the brand of spray. MR-97/Zyp works great. I have had problems with using high-temp 1800.
Also keep in mind that typically when you are using BN on molds, your temps are not that high. The higher in temp you go, the more likely that the glass and whatever it is in contact with are going to “stick” to each other.
Fused Glass Designs
dba Jester’s Baubles