Hey @DanielGraham!
I have not had an issue with newer or older links exactly. What I have found out is that if you are not logged in to the Commons, links to the content in Commons do not take you to the content. Any time I share links from the Commons, I include directions stating that logging into Commons first may be necessary. To log into the Commons, they will just have to open up Canvas, click on the Commons link in the course navigation menu, and then try the links to the Commons content.
Seems like a few extra steps, but logging into the Commons is different than logging into one of your courses. As far as I am aware, this method has worked every time.
I would love to hear if someone else has a different way of doming this. Hope this helps.