Here is what I heard from Canvas Support as of 3/2/16:
It looks like what is causing these two ePortfolios to fail is due to a problem that our engineers are currently addressing. The root cause of this, is any ePortfolio with a blank page (Blank Welcome page, or a completely empty page) on the right hand side causes the download to fail.
I deleted blank pages for both students in beta, and confirmed that this allowed the portfolios to download without any problems. That is a workaround that the students can use, but in regards to the blank pages, I'm going to escalate this situation to our support staff. That way they can troubleshoot further.
I hope this can help someone else!
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