Thanks for the prompt and helpful suggestion what likely went wrong.
I think you are probably right on -- I probably focused on the major title and went past the part that specified 401K, then through to the SEP part and didn't notice the extra step which wound up with the checkbox in the underlying form.
It might be a point of feedback to (somehow) make it clearer in the title that his part isn't about self-employed retirement in general, but specific to 401(k). Of course, looking at it in hindsight seems clear, but I do count myself as a careful individual (I'm a software engineer who deals with lots of details) and I still managed to click right through it... evidently.
Thanks
