Doesn't happen here, all PMDG 737 I have works perfectly fine, and same with the Fenix, of course. As I keep asking, all the time, make a precise, exact, example of a livery that doesn't work, and I'll download it and verify that.
But before doing anything else, be sure you have the current version of the installer, which you should always have, until either the antivirus or a firewall or a network problem might prevent the installer to update itself. Alternatively, use the Offline installer, which would at least prevent network/firewall problems.