Sadly, Adobe/LR have never addressed the issue where LR when stitching a panorama will tend to blow out a near highlight to the point of being pure white. Happens with all my tif or even raw files. I personally prefer LR for pano work as I only do single row, but the issue on high lights has been there from day 1. Same exact files worked on CC will stitch fine, no highlight problems, however CC only offers the content aware solution no boundary warp, and I prefer boundary warp.
Paul Caldwell