I've looked online and found that a long list of lenses is supposed to be supported in Lightroom, but I am only seeing a much shorter set of options when editing a JPEG image in Lr5.6 64 bit. The two lenses I most use (Canon's EF 100-400 L ISM 4.5-5.6 and Sigma's 70-200 OS HSM 2.8 are supposedly supported but not showing.
Any ideas how to enable or import them?
You have to shoot in RAW to get full support for Lens profiles. You'll always have a restricted list of profiles with JPEG.