@The_AntiTax_Man It's my understanding you submit Form 8453 and attach Form 8864 because ProSeries does not support the e-filing of Form 8864. It seems like its one or the other. Have you tried attaching Form 8864 and related documents to the return instead of including Form 8864 in the return? 

To assist to our fullest, we'll need a Sanitized file. Please contact support so we can guide you through e-filing or paper filing Form 8864.