One of the icons that can appear in iTunes Match, is the one that presents a cloud with a bar. In this case, the song is not loaded or in combination with iTunes Match to an error.
Unfortunately, iTunes does not provide information on what type of “error” has been detected but, probably in most cases, it is a coding error that may not even be perceptible listening to the song.
We can try to remedy it by transforming the song to AIFF; go to iTunes –> Preferences; in the General panel in the Import Settings, choose Import Using –> AIFF Encoder; will create a copy of the original song.
Then select the song origiale, that reported as error, iTunes also cancel it by selecting Delete from iTunes Match also. Then we go on the new track in AIFF, select it and do [CTRL]+click (or click with the right mouse button) and select Add to club. At this point the track should be uploaded.
We might have to play the upload because on some occasions after the first attempt, appears next to the track in a cloud with an X symbolizing the fact that the song has been removed from iCloud from a different computer.