When answering your own question, it currently says:
You must wait 0 hours before answering your own question
And it won't let me accept my own answer.
I did wait 48 hours. It was after the 48 hour time limit that it said I had "0 hours" to wait, and it would still not accept my own answer. Perhaps only minutes were left (i.e. < 1 hour). It should indicate that.