Hey @EvanCowan (or @HughLaverty if you know the answer to Evan’s question 
) ,
Could I ask whether you ever found a solution to this, please? I need to be able to assign multiple CMS Item IDs to a “member dashboard” (in this case, the CMS Item IDs refer to individual sport clubs from a “Club” Collection that the member owns and can manage from their dashboard).
Sounds like the same issue you’re having - it works fine if I only pass one reference (via Airtable), but as soon as I try to pass multiple IDs, Zapier freaks out. I’ve tried all sorts of separators to no avail. So at the moment, a member cannot have more than one Club assigned automatically using Zapier / Airtable.
EDIT: nevermind, managed to solve the puzzle! Massive thanks goes to @vanpaio - he has posted a workable solution (as well as a super helpful video by @MackenzieChild - watch it in full if you get stuck as this is what I followed) over on this post.
It essentially involves passing it through in JSON format to Webflow. That makes sense, given that the Webflow Designer is built on top of a huge amount of JSON! You will need to use Airtable to make this solution work - luckily, they have a free plan.