I have used Live Movie Maker for years and it has always worked perfectly. I bought a GoPro8 and captured some HD video which edited as expected. I then captured some 4K video and was required to purchase (from Microsoft) the HEVC Codecs in order to play the 4K footage. This worked. However when I next tried to use Live Movie Maker, the preview screen was black (so unusable). I thought perhaps it wasn't possible to edit 4K but then realised I was unable to edit any video resolution. Everything seems to point at the installation of the HEVC Codecs but, if I uninstall these, then presumably I would not be able to play the 4K?

As an aside, disappointed to be charged for the Codecs - not much but just the principle.