Dear Vinicius,
I tested it with the standalone R-udp-playerMojave, on OM 6.16, with the same setting in OM preferences:
osc-scoreplayer’ as the default scoreplayer and checked the option ‘force score player’
So maybe you should either:
scenario 1) trash the workspace preferecnces, and relaunch om, applying the same settings.
scenario 2) check your port, it could be closed, or unavailable.
By the way, are you using special hardware ? the error indicates that the port is unavailable, which seems strange.
Best
K