I'm a relative newcomer to BFD3, but have already had excellent results from it.
As I get more advanced in drum programming I like to partition my pieces into several sections in the track section of the groove editor. Sometimes I assemble these pieces from smaller fragments of drum parts and fills, like in the screen capture attached to this post.
I use these as a basis for further modification, but they are very clunky to edit while fragmented like this, so I prefer to glue them together using "Merge to New Part" from the menu available by right clicking on the track items when several are selected.
I would expect this to make a copy of all the existing parts in one place, playing back as they did before. Sometimes it does, sometimes it does not. When it does not, there are large blank sections where there used to be drums. I think this has something to do with parts that are truncated at the start, and parts that are looped. So the section in my screen capture doesn't fare well at all! If I avoid truncating or looping parts, the merge works as I would expect.
Am I missing something obvious? I've checked the manual but can't find an answer. Any advice much appreciated!