Gastrodon couldn't Protect!?

Question

I was playing a Showdown! match with my VGC team. It was 2-1, and I was losing.

My lone Gastrodon, at just over 50%, faced down a low-health Mega Manectric and a 74% health Landorus-T. Landorus used Brick Break, activating my Sitrus Berry and bringing me back up to above 50%. Manectric used what I assume was Hidden Power Ice, and then I KOed Landorus with Ice Beam. The following turn I Protected to see what Manectric would do (he also Protected). But my Protect failed! It was the turn after I used Ice Beam, so it's not like its success rate was lowered. Is it because Landorus used Brick Break?

Here's the replay. Said failed Protect occurs on Turn 13.

Comments

Presumably a programming error on showdown, maybe a fringe case where only 1 pokemon remains on each team and they both use Protect, so the pokemon with the slower speed stat has 50% chance to fail, because it's "already been used" this turn.
Just a guess though, I can't see any real reason why it should have failed.

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It was because he had already protected and you were slower. This also happens if they switch while you protect.

Answer 1

Its because he protected first. Protect Fails if you move last in a turn.

Source: http://bulbapedia.bulbagarden.net/wiki/Protect_(move)

Answer 2

Manectric had used Protect first, since it is faster than your Gastrodon. Manectric's protect activates. Since your Gastrodon now has no move to protect against or a possible move to protect against, your protect fails.

Also, note that had Manectric used an attack your Gastrodon would have protected it.