Premiere Pro uses two different importers to read QuickTime clips. Which one is used depends on the codec require. The current version of Premiere Pro CC reads captions only if ImporterQuicktime is used; captions are not supported when embedded in clips that require ImporterMPEG.
Until caption support is added for ImporterMPE, the workarounds are to use either caption sidecars or captions embedded in QuickTime clips that use ImporterQuicktime.
Well - that's consistent with the additional testing I've done. Any MPEG based codecs do not work - while ProRes, DVCPro and others work fine upon re-import. I could have sworn we had it working previously as we've been doing the export - reimport workflow since CCs release but I'll have to go back and look at the exact file formats they were using for the last few weeks. Perhaps someone goofed on our encoder settings and they were somehow going out to some non-MPEG format for a few weeks.
Hopefully getting the importMPEG function to work in a future update is high on the priority list.
Thank you for the response.
I also hope ImporterMPEG will include caption support. I am dealing with the entire Simpsons library from FOX in the XDCAM HD 422 50Mbit codec, and they must be downconverted and dubbed in real time through Premiere Pro CC. The captions do not show in the V2 line, and do not pass through on playback. This means I have 5.3 terabytes of unairable episodes until I get either an on-air playback system that supports direct drag&drop of this codec, or a fix that enables ImporterMPEG caption support.