Problem Importing Video Into Cubase Pro 8.5

I’m having real problems importing any video into Cubase Pro 8.5.20. I’m on a Mac (El Capitan) with the most recent version of Quicktime. Both the Cubase project folder and videos are on the Mac’s internal hard drive. I’ve got a variety of videos in different formats (DV, Mov, mp4, mpeg), frame rates etc… They all play fine in Quicktime and load perfectly into ProTools and Logic.

If I create a new Cubase project and select File > Import > Video I can then navigate to my video folder. The dialog box gives me all the spec of each video as I point to it. If I select a video and click OK to import, I might see a progress bar as Cubase imports the audio - then I get a Cubase “Import Options” dialog box with the options:
“Copy File to Working Directory”
“Sample Rate”
“Sample Size”
“Split Channels”
“Please, don’t ask again.”

Of these, only the last two options are available - all the others are greyed out.

Then, whether I choose CANCEL or OK, Cubase will lock up with the Mac’s spinning beach ball.

The only way out is to FORCE QUIT from the Finder.

Anyone else come across anything like this? Any ideas? Solutions?

Thanks, in advance!