When I enable lens corrections on a jpg image it brings up the wrong lens info. If I try to change it there are only 2 lenses listed—neither one is correct. It lists a 50mm lens even though in the Histogram just above it says 18mm. I then tried the original DNG image & it chooses the correct lens automatically. Both the jpg & DNG image EXIF info show an 18mm lens, which is correct, but Lr doesn't read the jpg info correctly. The problem is the same on all the images I've tried so far.
Most Adobe-supplied lens profiles are for raw files only. Since there are very few JPG lens profiles LR is probably just choosing the closest one it has which isn’t anywhere close to the right lens.
The reason raw and jpgs have separate lens profiles is because cameras apply lens corrections when they produce JPGs and it would be inappropriate for LR to apply a lens profile when the camera already has, so LR refrains. If you are sure that your camera has not applied any corrections then you can hack a raw lens profile into a jpg lens profile by text-editing a copy of the .lcp file that comes with LR, and changing the raw designation from true to false inside the file for each profile segment, then move this edited copy to the users profile area. You might also find the JPG version of the profile using the Adobe Lens Profile Downloader available via a search at adobe.com.