The HDRpanos which give the errors were indeed created with the latest 2015.6 update.
Starting with your original DNGs, using Auto Tone and Auto Align for the HDRs and any of the Projection options worked for the Pano, itself. Is there anything special I need to be doing? These images are different than what you show the error with, initially:
Also, I asked if the HDRs where created in LR CC 2015.6, the pieces before you merge them to a Pano, or are you starting with HDRs that you merged with LR CC 2015.5.1 or earlier, and just doing the Pano in LR CC 2015.6?