I used to have a 2008-era Core 2 Duo-based system running Studio 12U(patched).  I fed it from a Hauppauge HD PVR running the original Hauppauge SW, and it worked OK for my use cases - editing highlight reels from sporting events recorded off cable and editing commercials out of recorded shows I wanted to keep.  I recently built a new machine, upgraded to 19.5U, and upgraded the capture SW to Hauppauge's latest.  Now, I cannot import any file captured using this new setup (M2TS, TS, MP4 - doesn't matter).  Interestingly, I can still import files captured under my old setup.

Details:

Studio Ultimate v 19.5.1.401 (64-bit) / Hauppauge Capture v 34057 (16 FEB 2016).  Error message is "<name> appears to be of a size or type that is not supported."

Rig: i7-6700K / GIGABYTE GA-Z170X-UD5 / EVGA GeForce GTX 950 / Corsair Vengance LPX 32GB / Win7/64-bit