I have an issue since I installed, then UNinstalled the Bandlab version cuz it ignored all of my customizations.  NOT COMPLAINING!! Don't put me in Max Security.  Anyhoo, now my PreSonus FP-8 doesn't respond to Platinum no matter what I do.  PreSonus says their FP-8 works fine on their Platinum install.  They're still looking at my Sys Info file.  I've checked my BIOS, Windows Updates, etc, etc, etc. Any ideas. 

No, only that after wasting weeks sorting out a problem coming up with an unbelievable answer on the Presonus forum ... I avoid their hardware altogether. I limit my involvement to their DAW. 

You are resetting to SONAR mode on power-up, right?

Did you exactly follow the setup procedures for the FP8?  I can't tell you how many times I've seen users mess up a USB-device install because they hooked up the device before installing the software.
 
If you followed the instructions, try connecting to a different USB2 port.  Avoid USB3 if you have a choice.
 
Failing the above, you will probably require a clean reinstall of the FP 8 and/or SPlat.  (By "clean", I mean uninstall, clean registry, then reinstall.  I would start with the FP8, since it's easier).

Make sure you have aftertouch enabled in the Playback and Recording tab of the MIDI section of the Preferences. FaderPorts won't work without that enabled, and it isn't by default in SONAR/Cakewalk by BandLab.