[Matt Mulrine]

Had this problem before, very annoying that no one had the answer. Through a leap in logic I eventually thought maybe it wasn’t a problem with the files but with associated metadata in the folder structure. I was right. To fix it move the mp4 files elsewhere, I can’t remember if you need to keep the folder structure or which file was specifically causing the problem maybe something like an xml file. I figure what happens is that when you merge the clips they do merge but the EX software doesn’t change data in the external metadata files so Premiere seems to think it can’t access the files (even though it can if you move them so that it doesn’t read the other files).

If you do this and the Premiere media browser isn’t reading it then simply go file import instead.