The combat log shows a string of consecutive misses with 95% hit chances.
Springboarding from this, I'm testing OSA now.
We can see that the streak breaker is active in this screenshot.
Successful hit rolls are also shown, but only the first few, after which... at a guess, the chat engine is suppressing further messages as spam, either by design (so players wouldn't have to sort through them to see how much damage they were dealing) or by accident (if the chat engine wasn't set to ignore spam from powers the same way it ignores spam from player accounts).
The "Your Oil Slick power is autohit." message bothers me, as there isn't a single entry showing auto-hit in CoD. I've combed through every pseudo-pet and power, none of them are auto-hit. So there's something hidden, even from direct data diving, or there's something wrong with how CoD is reading the data ( @UberGuy, investigate, investigate, investigaaaaaaaaaaate!)
In this screenshot, I do have two misses shown consecutively, but we can chalk that up to either the chat window showing things non-sequentially, as we've already seen that the streak breaker will force a hit at the appropriate time (in this case, after a single miss), or enemies exiting and re-entering the AoE, thereby altering the target list (AoEs use a specific pattern for targeting and hit/miss checks... someone, i don't recall who or when, mentioned it being clockwise from the center outward, but i haven't examined it myself, so i make no assurances on that).
I'm going to agree with @Booper. @TimesSeven, it's looking less like a bug and more like you only had hit rolls enabled in the chat window, not damage, and given that the chat window stops showing hit rolls altogether unless there's a miss, it's likely that you've only recorded misses for exactly that reason. Try again with Pet Damage Inflicted enabled.
It doesn't, but it has a 25% base Defense Debuff, which is enhanceable, and that's far superior to any amount of +Acc.