Premiere Elements 11 Generic error fix.
November 8, 2019:
I think I figured out what causes the generic error message. Using Filmic Pro on my iPhone 8 Plus, I created a 4k video using the "High Efficiency codec (HEVC). Then I disabled the HEVC option in the "Resolution" section of the Filmic Pro settings, and made another video. When I tried to add the videos to Premiere elements, the HEVC video resulted in a "generic error" message, but the video shot with the HEVC turned off was accepted into the project assets of Premiere Elements.