I have a LG NANO90UNA. I run the plex app for WebOS. I have been trying to figure out how to get Dolby Vision movies to play on it and I finally solved it. I have only found that it works with MP4 and not MKV. The library type also is a big factor. The library needs to be specifically set to “Other Videos” in the section where you select if the library is movies, tv shows, etc.. I have not been able to get any Metadata to work with it so its just going to show up as the file name and maybe a screenshot. But its a step further than I have gotten before. I tried with MKV but the colors still remain in that green and purple tones. MP4 is the only thing that activates the Dolby Vision on the TV. I tried to play a movie from the same library on a 4k DV Firestick but had no luck getting it to play. I do not know if this works the same way on other LG or other Dolby Vision TVs yet as I do not own anything else. Hope this helps.
Update to this post 7/722. The new LG WebOs Plex update seemed to solve the library type issue. This now works to set it as a movie library so the metadata collects.
