How long do you purge? have you tried to run the slab over night at -600 mm hg at 85f then take out the slab out and let it sit for a half hour, then lower temp to 70 and run for 4 more hours? Try lower temp with strains that come out sticky. Just repeat the process until you achieve stability (about 3 times).
Im also beginning to think your hands on experience is little to none. If i have material thats more the 30% activated thc (30% decarboxlylated) THERE IS NO WAY its gonna come out a shatter at room temp(75F). I run my extraction process at -40F and purge in a dust form at 60F to 70F for 48 hours then heat at 120F to melt into a slab for the last 12 hours. 0ppms every time through analytical 360.