Sheets listed but missing
The app is not live yet. This article describes the intended behaviour. planned
When the sheet index and the files disagree
A drawing set prints its own sheet index, usually on the cover sheet. The app reads that index first. It then looks for each listed sheet in your files.
If a sheet is listed but no page for it is found, the Index Report names it under "Listed in the sheet index but not found".
Example project (fictional): the index on Sheet G-001 lists Sheet A-401. No page numbered A-401 is in the files. The report says exactly that.
The report does not say why. The sheet may be absent from the download. It may sit in a file you did not upload. It may have been left out when the set was issued. The app cannot tell these apart.
Sheets are identified by the number and title printed on them. The app does not guess a sheet's content from its number.
Sometimes a whole part is absent. Specifications may arrive with no base drawing set, or drawings may arrive only as addenda. When the app can see this, it puts a note at the top of the Index Report.
To resolve a listed-but-missing sheet, ask the issuer or the plan room for it, then upload it into the same project.