According to my chat logs there were no yells about phase 3. However, I have BigWigs' BossBlock enabled for the following three events: Boos emotes, Raid chat, Raid warning chat messages. I'll disable those and see if that resolves the problem.
Boss block has nothing to do with it. Does the enrage bar show up on phase 3? I made a change that may or may not fix it.
At what point is it supposed to re-enable Master Looter for phase 3? I understand the default for this behaviour is off, so if I've unchecked the option it should enable ML for phase 3. However, phase 3 begins and the looting option stays on FFA.
The addon works beautifully for setting loot to FFA, at least. :)
I'm going to guess you're not using the enUS client, and the yell for your client isn't translated properly.