You have a few options - you can disable TCP sequence randomization based on an ACL match; or you can not log any of those messages. The latter will disable the messages altogether, not just for a specific IP, while the former will still log packets...
Not sure if you ever got this resolved, but I came across the same thing and found your post. I'm assuming you added an ACE to the ACL used by the class-map, and were surprised when the Connnection Events in SFR still showed that traffic?
What I foun...
Came across this while looking to see if that bug was fixed - that's me you quoted from reddit :)
Here's the official bug ID from Cisco; no resolution as of yet. https://bst.cloudapps.cisco.com/bugsearch/bug/CSCuz03275
I just went through this with TAC. They pointed out that the documentation states that you should not sync SFR with a virtual FMC. I wound up setting FMC and SFR to pull time from my domain controller and all was well.