Server Version#: 1.23.0.4497
Player Version#: client 5.14.1 platform 10.0.19041.7339
Hey guys - bumping this since my last thread got closed after 3 months with no replies 
On my Series X when I try to direct play 480p (720x480) content, it does not properly display it in 640x480, it shows the full 720x480 which results in a stretched out image. If I force it to transcode by changing the quality it does play in the correct 4:3 aspect ratio. When I play the same file on my Xbox One or through the plex kodi add on on the Series X it direct plays just fine in the correct aspect ratio, so it seems to be specific with the native app in the XSX (despite being to my knowledge the exact same app as the Xbox One). Should probably point out that this is HEVC content.
Any ideas?