Never seen this before, I'm clicking on o or m keys, and it's not cycling through the tools. I thought it might be my keyboard, so I tried another keyboard same thing.
Thanks Jeff! Yes I remember that preference form 15 years ago.
You are right.
My next question is how did that get checked? I have not gone into that preference area in long long time.
Hard to say, but usually that is the default in photoshop, unless the user unchecks it.
Maybe the photoshop preferences have been reset at some point?