There is a known issue with Edge 40 failing to release the camera after stopping local media. The Edge team is aware of the issue. It is reported here: Camera activity indicator remains active after stopping tracks, when acquiring an audio video stream. A side effect of this issue is that subsequent attempts to get access to the camera can fail, even when using other browsers/platforms.
A second known issue is related to muting the video stream. Muting the video stream in Edge 40 stops video from being streamed, but it does not send zero-information-content as per section 4.3.1 of the Media Capture and Streams W3C Candidate https://www.w3.org/TR/mediacapture-streams/#track-enabled. This results in the last frame being displayed in both the local and remote views, which makes it appear that the video has been frozen instead of muted.