I am having trouble with my Octane 45 on my Glock 20. The gun will frequently lock open with rounds still in the magazine. It locks all the way back, slide stop engaged. The gun functions perfectly un-suppressed. I am using a KKM barrel. The suppressor booster and O-ring are well lubricated with lithium grease.
I initially thought it must be way over-gassed, so I tried the following things to slow down the slide:

1. Heaver recoil spring (Wolff) up to the 24 lb maximum
2. Extra power magazine springs
3. Hand loading subsonic 10mm (200 gr @ 950 FPS)

Even with all three together, it still locks open prematurely. I don't have any other guns to test the suppressor on, but I can't imagine the suppressor itself is the issue (sounds like it's working very well). Could it just be all the extra weight on the end of a tilting barrel that's causing the problem, rather than too much gas? I would really appreciate your help, given how long I've waited for this suppressor! I was thinking of getting a Glock 19 as well, but don't want to have the same issue if it's a Glock thing.

If the slide is locking back with rounds still in the magazine it can not be the magazine follower pressing up on the slide lock.
But, if it is being engaged, so it has upward pressure from:

Inside- maybe bullets rubbing

Outside- are you sure your grip is no where near the lever?

Inertia- make sure the spring that hold the lever down has enough tension.

Does it happen regardless of ammo type and number of rounds in magazine? Have you tried different magazines?
Does it happen one handed or with your off hand also?

I have a Glock 20 KKM barrel, GA Revolution 45 and have had no problems at all.