iTunes won't relocate my music files

The beginning:

I've been transferring my LPs to CD for months now. I've been importing my CDs into iTunes without any problems. By the way, my iTunes library resides on an external HD. Then one day, I opened iTunes to import another CD and noticed all of my existing songs were not showing up in itunes. I tried several things to no avail.

So, I did the hard thing. I completely uninstalled iTunes from my PC and made sure to delete the folders, too. I then downloaded and installed it. The version I got was 12.3.1.23.

Imported a cd. The songs went to folder C:\Users\Martens\Music\iTunes\iTunes Media\Music. I changed the preferences (Edit/Preferences/Advanced) to point to a thumb drive. Itunes asked if I wanted it to ‘move and rename’ the files. I clicked Yes but nothing happened. The music files did not move nor did they show up on the thumb drive; but the preferences now point to the new location.

So, I went to the menu (File/Library/Organize) and selected both options (Consolidate and Reorganize). This time something happened. A popup window showed files actually being copied to my thumb drive. I know, right there on the screen the consolidate option says it ‘copies the files’ and leaves the originals
behind. I manually deleted the music files from the original folder.

So now I have itunes pointing to the right folder but what I can’t figure out mow is how to get itunes to recognize all of the missing music files.