The option "Use Project Output Rotation setting" in Render Options simply doesn't work.
Assumed the project property is set to 16:9 frame size (e.g. 1920x1080, not 9:16) while rotation is set to 90°, that render option does nothing. I tested with all the video codecs available in the rendering option and none of them worked.
I had to change the Width and Height values of the project in the Project Properties settings and also in the Custom Codec Model to get a correct 90 degree video orientation.
By doing so it is possible to render correctly on some Intel HAVEC codecs, MAGIX ProRes, Main Concept AVC/AAC and Video for Windows AVI. The other codecs do not render correctly or simply do not render.
More information about this issue in this Vegas Pro forum link.
https://www.vegascreativesoftware.info/us/forum/90-video-workflow--106019/#ca681339