When you say, "The 3 dots don't show up" are you referring to the three dots to the left of the red video recording button in Flipgrid? I have not heard of this particular issue with Flipgrid before, which is unfortunate because that is what I would recommend using (clicking the three dots and then using the screen recording feature to record as you interact with the graph). Unfortunately, the only other way I can think of to address this issue would be to use a screen recording app to record your video (such as screencastify) and then uploading the video instead of recording through Flipgrid itself.
Maybe someone else has dealt with this issue in Flipgrid?