4.53.2.37456 TDA on Windows 10 but issue also present on previous version.
When I go back and forth between tabs under the Riders section sometimes other riders show up under the "Myself" section.
When I tick the checkbox and want to start a ride with them the error message "An error occurred while trying to start the workout".
These riders are not listed under the "All" section. Maybe they have Live Opponents/Share Live Activity disabled? In any case they should not show up under the "Myself" section.
See image below for an example.