Thanks for the reply.
In the first clip, I kept it progressive all the way through, yet when exported to h.264 720p 29.97, the result has jaggies typical of interlaced footage.
The strange thing is, when I interpret the footage in Premiere and conform to lower fields first interlaced, then export the exact same way (720p 29.97 h.264) the result looks fine (2nd clip).
I can’t figure out an explanation. It seems to be working–but I know something is off when I have to interpret footage that I know is progressive as interlaced.
Could it be some kind of glitch in Premiere?