I posted this issue on the Adobe Forum, but thought I would post here as have not had any response yet.
I have a feature doc edit project with hundreds of hours of .mts footage that originated in Premiere Pro CS5.5, updated successfully to CC (2015), and now needs to be updated to the latest release of Premiere Pro CC (2018) 12.1.1. My editor only has the latest version or Premiere and Adobe does not offer earlier CC versions, as far as I am aware.
The Media Browser function of bringing the project in sequence by sequence (the method I used to bring it into the 2015 CC Premiere software - tedious and time consuming and required a lot of organizing, but it worked) is not functioning: the previous project file does not load correctly when selected - the progress bar goes all the way across and then nothing happens.
My current workflow: I opened the project from the CC2015 prproj file, Premiere automatically created a new version of the project, and it took 12+ hours for the media to load and 4 or 5 times that for all the files to conform. Now when I reboot and reopen the project, premiere zeroes out part of the media cache files (.cfa files mainly, as far as I am aware) and rebuilds them - conforming seems to go on endlessly. This is a problem - the project lags and acts sluggish while conforming is happening, unresponsive and video will not play smoothly.
I have the original media files on an external 7200rpm 8TB drive and the media cache and preview files are set to go to a separate external 7200rpm drive (1TB).
Media source codec: AVCHD .mts (Panasonic GH2)
2013 Imac / macOS Sierra
Same issue with this update. First I had to rename all of my .mov files to get both video and audio on import into project. Prior to renaming, only audio would import. Now that I have the media in the job, the playback is laggy and slow. Looking for help.