Yes, it was. I think I found the issue, and had nothing to do with UPLP. I created a list, pasted the short code into a Modal(Popups v1.8) and that seemed be throwing the error. No worries, I think for this I will add UPLP short code to a post and be done with it. But, seems like an issue when pulling posts per ID into a modal when using the Popups plugin.