Are you using a MAC? I called Avid and got some half answer about how macs don’t support MXFs, which is false. However I tried importing the problem clips on a PC and it worked. I really don’t know what the issue is or how to import them using a mac. If you don’t have a PC or its still not importing, you can always digitize the clip in capture mode. I suggest digging in small chunks because of time breaks.
When importing MFX they are automatically named CO##. You can use Sony’s free logging software. Just import the proxys, name and log clips, export as ALE. Once you have you ALE you can drag into Avid. Make sure the source number on the imported clips is the same as the clips from the ALE. Then relink the ALE clips. They should link to the imported clips from the same tape.
You can get the software here. Hope this helps.
https://www.sonybiz.net/biz/view/ShowContent.action?site=biz_en_GB&contentId=1167924779651