Error (-12894) iTunes AAC conversion problem to iPhone

When I try to copy songs to my iPhone with "Convert higher bitrate songs to 128 AAC" I have a lot of problems. I tap on the song on my phone and it skips over the song. Sometimes the error -12894 will come up in a notification. This doesn't happen to all of the songs, but most of them. I've tried deleting the songs and re-syncing, same result. I tried turning off my antivirus software and firewall. I tried organizing the library. I haven't tried unchecking the convert box and resyncing all the music, but I'm worried about losing more music than just the few songs that won't copy.

Can anyone help?

Thank you!