1. On the left navigation panel, click on General > Electronic Filing > e-file PDF/Miscellaneous;
2. On the input screen, in the top-right corner, click on the blue hyperlink e-file Attachment in tiny prints; and
3. On the line "Link to form (defaults to main form)", select Form 7203 > 98 - Form 7203

The critical diagnostic was triggered because you did not link the attachment to Form 7203 and the system thinks that it's still missing.

@ForensicCPA, this might be what you're looking for?