There seems to be a difference this year when inputting multiple Capital gains worksheet codes including M for attached PDF files. When you add a second code W say for wash sales Form 8453 pops up again in the Forms in Use column although it is totally blank. In prior years Form 8453 would disappear altogether once you indicated you were attaching a PDF.   If you only have a single code M Form 8453 will disappear from the forms in use column.