Did you actually boot from the installation disk and run Repair Disk rather than Verify Disk? If you merely verified, that does not effect any repairs. You need to follow the instructions in Mac OS X - Using Disk Utility to Repair a Disk.

I apologize if you did this but I thought it best to clarify. I can't answer your question about the Lost And Found folder.

Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365