I can't figure out why some markers can have a non-zero duration, but others are always 0:00:00 despite trying to drag the time-duration or type a new duration. I tried un-linking stereo clips, etc., but I can't determine why.
You need to 2x click the marker to open it and then assign it a duration value. The default is 00.
I'm not sure why some of your markers already have duration but it could be because they had markers already added to them in prelude (or perhaps an earlier version of PrPro). So those markers and their assigned durations were inherited at import.
Thanks James. I wasn't clear - when I click on the "Duration" time slider, nothing happens. If I type some numbers, it "pops" back to 0:00:00. If I try to slide it to a greater duration, it pops back to "0:00:00". As if it's not allowed. But that behavior is random -- on other clips, the duration setting works as expected. I can type a new duration or slide to a new one with my mouse.