[noggin]

Is Dolby Vision supposed to work in Kodi 19.1 on AFTV4K? I have a file that when played by Kodi on AFTV it has the green/purple colors and the TV Dolby Vision notification does not come on. The same file plays fine on the same AFTV via the Plex player and Dolby Vision comes on on the TV. Also, same file plays in Kodi on the Google TV Chromecast.

That's normally a sign of a single layer ICtCp instead of YCbCr/YUV encoded HEVC file being played back as if it were YCbCr/YUV - with the I channel mapped to Y, the Ct and Cp channels mapped to Cb and Cr, with no conversion - I believe.  Single layer DV, professionally mastered, is usually ICtCp colour-space encoded.  

However there are non-standard single layer DV files created by software that rips DV UHD BDs, and that approach takes the HDR10 YCbCr/YUV Base layer, ignores any DV Enhancement layer (often - but not always - the Enhancement layer doesn't actually include much), and just muxes in the DV metadata RPUs (that metadata provides improved tonemapping/display of the HDR10 Base Layer (plus additional enhancement layer data that may get you to 12 bits) on DV displays).  That non-standard (?) DV file will be in YCbCr/YUV format - and so will usually be less problematic.

Bottom line - not all single layer "DV" files are the same, and not all playback sw+hw solutions can currently cope with all flavours.