It sounds like it might be a magazine problem. Snap caps will always work when you either drop them in or chamber them one at a time but if, for some reason, the magazine is bulging or there is something impacting the movement of the trigger bars then it is a maga problem. I note that on my Taurus PT1911 in 38 Super there is a adjustment screw in the trigger. It may be that this screw is a bit too far forward or rearward and needs to be adjusted. Or it could be a combination of both.
If the mag is bad, toss it and get some Mec-Gar or Chip McCormick mags. If you look at the mag and see some wear marks on the side, where the trigger bars travel, I just put them in a vice and squeeze'm a bit tighter and see if they work then..