Did you ever resolve this? I am having the same problem. I work natively with HDV 1080i60 (I know ProRes is better, but don’t have storage space) and I have been editing with it for years, never this problem…now it seems to do it ramdomly..the exact same thing you described, huge data rate size, tiny in size and pixelated horribly…
All of my settings are correct there is no basic mistake of different codecs or anything of that nature..if I export segments, they look perfect..if I export the whole timeline, crappy…if I export with QT conversion, the export looks fine (although I lose detail…)
Help…