- (maybe obvious, but) are you logged in as the correct user? (I can only see one
eed3si9n, so I don't think this is the problem, but sometimes people start with an unregistered account and then have a different registered account - which can be merged by moderators if needed)
- Did you have an (unsuccessful) bounty or anything like that?
Update: I checked the logs; yes, you did:
eed3si9n -> Bounty creation of 100 rep on question id = 490627 Feb 4 at 5:33 () (-50 rep)
If you add a bounty, then the ability to select an answer is removed after the bounty ends. You didn't select a winner, and none had 2 votes so none was auto-selected. See also Questions where answers can not be accepted, should not count towards the accept rate