Downloaded photos appear in imports, but are not showing in the library in the Photos app

Often when we hear this complaint, the actual explanation is that the photo bears an odd date/time capture stamp, so it appears in an unexpected place in the views that are ordered by capture time. Have you tried using "Show in All Photos" in the context menu on one of those photos?

Photos needs some time to index the photos in the library. As long as they are showing in Imports, they have been imported, but they are not yet ready to use. I would wait and not touch the new import, until they are showing in the library, particularly, if you are using iCloud Photos. jJust check, if the capture dates are correct, as recommended by markwsn.

@Mark: Mark, if you are also using Sonoma, have you also noticed, that ctrl-clicking a photo in Imports or Recents, then using "Show in All Photos" is no longer working well? The first few hours after an import the "Show in All Photos" is showing sometimes a completely different photo. The next day it will be back to normal.