aperture not recognizing PEF raw photos file (and it has in past with no problems)

Aperture is no longer recognizing my Pentax formatted RAW pictures from my camera.

I get the error message "Unsupported File Format" for all the photos I just downloaded to Aperture.

The photos show up in Preview with no problem.

It has always worked in the past (I use Aperture frequently).

Why now all of a sudden.

Running 27 inch iMac bought new in July 2014 with OS 10.11.3.

Since El Capitan OS I have had many issues with Aperture.

I like Aperture a lot but this continued issue problems are making me to consider changing photo programs

Any fixes or should I just get another photo program?