I can't migrate my characters to SSF Standard

I tried to migrate them all by clicking the >> button then select the league I want to migrate to, then it got stuck in queue 0 with no progress at all. I canceled it to make another attempt but I no longer get the option. When clicking Migrate or Migrate All beside the character, it will remove the SSF status of that character. Is this a bug or something in the server that won't let me migrate to SSF Standard?

Phrecia?

Phrecia was not a normal league, it was a sub-league/event, hence SSF only migrating to Standard (which is the usual choice for events, to migrate from SSF to non-SSF).