I have experienced two squib loads in my time, both using H110 powder in .45 Colt. These were due to insufficient neck tension and/or a loose crimp.
I returned home with the unfired ammo and ran it into a crimping die, adjusted to obtain a tighter crimop, and everything worked fine. Winchester 296 and Hodgdon H110 are notorious for not giving optimum results with very light bullets and not enough bullet pull.
In my case I was using CCI Magnum primers, Winchester brass, and Hornady JHP bullets. The primer fired, driving the bullet up into the bore and sort of "pelletizing" the powder charge.
I keep my powder sealed in its original container until use, and re-cap it after and never been plagued by high humidity.
New Orleans invented high humidity, Memphis improved on it.