Music in Catalina cannot find files when I choose a different music library

tt2--Thank you for the reply. I have read your posts before, and they have always been helpful. I am sorry for the delayed reply on my part. Since the post, I deleted all the music files on my external hard drive and then started the process anew of copying them back to the external drive. Now, the files are playable. I see no exclamation marks and the few songs I clicked on played. I can't see the entire file name when I check the file path through "get info" for the songs, so I am not positive Music is accessing the external drive. Is there a way to see the entire file name of the song so I can check the file path? I didn't take any different actions in copying the files or accessing the drive when opening Music than I did the first time I tried this. Seems a strange glitch, but I am glad it is working--at least for now. One last question, after I choose the itunes.itl file, I always have to save a copy of Music. I have as many saved folders as I have chosen different libraries for Music to play from. Is there any way around this or will I just have to continue to save the files as Music 1, Music 2, etc? Thanks again for your helpful replies. (For clarification, I have added a screenshot of the file path and the "save" message after I choose itunes.itl from the external drive.)

Thank you for the clarification. Does it matter where I save the newly converted library? i.e. if I am running Music from an external drive should I save Music 1 library to the same external drive or to the computer's hard drive? Also, I noticed that a few of the albums that are in the iTunes Media folder are not showing up in the Music app. The Mp4s are in the artist's folder. The albums that aren't showing up are newly purchased and downloaded from iTunes. Is there a way to get these albums to show up in the Music app?

Thanks again for your help. I am going to reread your post on making a split library portable so I can try to understand better what is happening with the Music app by changing the location of the library. The transition to running Music from an external drive has not gone as smoothly as I had hoped--trouble ejecting the hard drive when I want to use it to play music on another computer and then trouble finding the proper library again when I reopen Music. I am not sure what I am doing wrong, but occasionally, Music can't locate the files even though the file path appears to be correct. So far I can get it all to function after taking a number of steps, but I am still having trouble with Music locating files now that the library has a new location. It has taken a lot more time and energy than I expected. Thanks again for taking the time to share your knowledge. Greatly appreciated.

Thanks for the tip on saving the converted library into the /iTunesMedia folder. Since doing that, I haven't had the trouble of ejecting external drive because "one or more programs are using it." Quitting iTunes and opening with a different library still wouldn't allow the drive to be ejected. The only fix I could find when that happened was restarting the computer.

Also, I moved those missing albums to the /itunesmedia/music folder, but I still couldn't find them in the Music app either searching through albums or using the search bar. I ended up clicking on the individual Mp4s for each album and then I could both see and play them through the Music app. Seems strange those few albums wouldn't show up in the Music app despite being in the itunes music folder.

Another question regarding adding new music to my library. If Music is accessing the external drive for the library, then any music I add to the library either download through iTunes or importing CDs should automatically be added to the music folder on my external drive and not my computer's hard drive, correct?

Thanks again. Very helpful.