Hi Gunther,

Haven't had this issue before and I have a feeling it is happening because I exported the TIF files from lightroom in 2 separate times (yesterday the first 350 photos and today the remaining 1000). I then renamed the files so that they would order sequentially (E.G. "Monument (1), Monument (2), etc.) but when I go to File, Render Video, I get this message.

Any idea why this is happening and if there is an easy fix without having to re-edit and then re-export out of lightroom?

Try renaming the images like this: LRT_00001.tif etc. Put them into a folder, which name starts with LRT_

That did it, thanks very much!