I don’t know why you could have lost SR on a different role and you may need to report that as a bug. Unfortunately all disconnections and game crashes counts as leaving the match and will be penalized. The game server has no way to discern a legitimate disconnection or game crash from one that is forcefully caused by a dishonest player to bypass leaver penalties. You can learn about this policy here:
Did you disconnect or crash (please be specific), troubleshooting is available but we need to know more about your specific issue.