imported photos not showing in Lightroom

Can anyone give me a solution to a problem I've got in Lightroom Classic? I had a very large folder that I imported into LR but some of the files failed to import. I then did a second import of the rest, but now only the ones from the second import are showing. The first lot are definitely there and they show in the Catalogue under "All folders" but not under the folder itself. I'm working on a Mac.

Thanks in advance!

By @jane ma1951

Sounds like one import was done using COPY and one import was done using ADD, and so the photos are in two different folders.

Did you perhaps copy or move the images during import inadvertently? In that case they are in another folder than the original folder. To find out where they are, select one of the images while you are in 'All Photographs' (Lightroom does not have an 'All Folders' collection) and then choose the menu 'Photo - Go to Folder in Library'. Lightroom will jump to the folder in the folder panel where this photo is stored.