I'm currently working on a 6 camera multicam edit of a concert I shot a few weeks ago. I converted all of my h.264 files to Prores Proxy for the edit, and then reconnected the proxies with ProresHQ files to do a minor color grade. All the files reconnected correctly, but when I rendered out my sequence all the files seem to look like my proxy files. When I check the item settings for each file it says they are ProresHQ.
I exported a sequence at current settings and it gave me a proxy quicktime file. I did another export but manually switched the settings to ProresHQ and the files looked great.
I'm not sure what I'm doing wrong at the render stage.
All my RT settings are set to playback at High Quality and Full Frame Rate.
Sounds like you didn't switch the sequence settings to ProRes HQ. Open your sequence, press command-0 and change the compressor to the proper setting. I'm guessing you just manually pointed the sequence at new media files? If that's the case, then FCP won't automatically update the sequence settings. Once you make the change, you should redo all your renders to make sure they are done at HQ quality.