Handheld Sync works fine for a Classic iPod using the 64bit version these days, as it is just treated like a hard drive in Windows, so visible in the same way with MC. I would dare to say most Android devices work with Handheld Sync, but there still seem to be a few that pose a problem. Hendrik has fixed lots.
The "File not supported" in the status column means that you have a setting wrong.
Check the "Drive & Devices > {your device name} > Options > Files, Paths & More > Supported Types" or "Options > Handheld > Files, Paths & More > Supported Types"
If that is set to "*", then all file types are supported. If that is set to "mp3;flac;alac" then those three file types are supported.
I just set mine to "*" for simplicity, and control what is transferred using the Playlists I sync. But the intent is that if you are syncing to a device that only supports mp3, for example, then that setting should be set to "mp3".