Recorded two separate streams using Mevo. Downloaded copies of the streams to my PC. Both MP4s play fine on the computer; both audio and video. When I use one in Camtasia 2018 it works fine. When I use the other, the audio component of the video is missing. There is no audio. The audio options in the popup for the video clip on the timeline are disabled. I can't export the audio either for the same reason. It's as if Camtasia thinks the video does not have audio even though other media products recognize that it does have audio. Suggestions?