FCP X project from 2013 uses GoPro Cineform codec, now can't seem to update

I'm wanting to open up an old project from 2013 that uses footage in the GoPro Cineform codec.  
All the footage now is "red" with the Missing Plugin notice.

I have tried dropping the footage onto Compressor to convert it all to ProRes, but Compressor won't accept the .mov file either.
What DOES accept the footage is Adobe Media Encoder, so I used it to convert all the footage to ProRes.
Thought I was in the clear, but then when I tried to relink in FCP X, I get an error that the footage has to be the same frame rate, length, etc; basically it won't let me relink to the new converted ProRes footage.

Any ideas how I can get around this?

Well, things have been changed since 2013, 8 years is a long time. I've not worked with GoPro footage in a long time. I thought GoPro had their own app to convert/conform their own footage.

You'd have to reconnect to the original codec, etc. You can convert and reconnect like that.

So is it a missing plugin notice, or a missing clip media notice? They're two very different things.