It's not consistent, but a variety of issues often occur when exporting tagged files for 508 compliant PDFs. I often have to backsave to v.14 and all works fine in that. Sometimes I will get a pdf that has artifacts or other elements that have different tags than those assigned in the InDesign file. Sometimes I get urls that won't read on the read aloud function. Sometimes things work fine. It's happened often enough that it seems to warrant attention.