It might be just me because I installed a whole bunch of beta `sdk's on my mac, but before I could go into a pdx file to inspect pdi and pdt files. with Nac's quicklook feature. (press spacebar with a file selected to see a window with a content preview).
Not really worth creating a bug for, but... broken for everyone or just me?
Another trick that often gets Quicklook working again for me is restarting the Finder, either killall Finder in Terminal or option key+right click on the dock icon then do Relaunch