I had a chance today to shoot my Sig MPX with my Omega 9k suppressor.  At 25 yards there was a POI shift of 6" with the suppressor mounted.  With the the can the rounds were landing 6" higher than when the can wasn't on the gun.  That seems excessive but maybe not. It that to be expected?  Just wondering if something might be wrong. I look forward to hearing from the pros.

From my experience, impact shift are quite normal with a can attached due to the changes in turbulence of the exhaust gases.
Even just re-crowning a gun can result in some shift.

What matter more is if it's a consistent shift (preferable consistent between removing and re-attaching the suppressor) and a simple re-zero is taking care of the issue.

Ill be the first to admit I don't know much on the subject, but 6" seems like a lot to me, especially at only 25yds

I was able to visit my Omega 9K in jail again today to try and figure out why I was getting such extreme POI shift. When I mounted the 9k onto the Sig MPX via the HK parts 3 lug adapter there was noticeable play. I called SiCo and was told by Quentin that some play/wiggle is inherent in all 3 lug designs. I removed the 3 lug adapter and used my direct thread attachment and Eureka, there was no noticeable POI shift at all. I already paid $140 for the SiCo Octane 3 lug mount and I really want to be able to use the 3 lug mounting system. Since it looks like the HK parts MPX 3 lug adapter caused my POI shift issue, is there another 3 lug adapter that might be better?  I guess the SiCo octane 3 lug mount could be the problem as well.

I have an 716 16" barrel  that I get a big POI shift about the same as your  6" high to the right. The can is a Yankee Hill direct thread. I use the same can on a DPMS with a 24" Bull barrel and I get very little POI.
I tried two type of ammo 146 gr 168 gr that I used  same results.