After upgrading to Windows 10 from 8.1, in Lightroom 6 the names of my previous Print Templates appear in Template Browser, but their settings are not read properly; page sizes are wrong, icc profile is missing, etc. In C:\Users\Ken\AppData\Roaming\Adobe\Lightroom\Print Templates, the text in the template files seems to specify the previous settings correctly. Thankfully, all is backed up on an external drive.
How do I get LR6 to properly read the settings in the previous template files? Of course, I would prefer not to have to deal with each Print Template individually.
Please reset the Lightroom preferences back to default and check if that helps.
Press the shift + option keys immediately after you restart Lightroom, and select Reset Preferences from the resulting dialog box.