I have come across several instances of teachers reaching out after creating a quiz, sharing the quiz with another teacher using "send to" and then the recipient can see it in their 'shared with me" content, but when we try to import it into a course, it never comes over.  Right now the only workaround is having the originator of the quiz export the quiz, email the zip file to the recipient, and supporting the recipient in importing.  But honestly, that only works 50% of the time.  I couldn't get it to work for myself, but it worked for others.  These two teachers do not share a collaborative course, so that is not an option.  They do not have the ability to add this to the commons.