Hey now, that's not nice. Salazar is a Castellan, he deserves at least a little respect.
That happens when a specific switch is turned on. Which Maid you have with you can matter during this update, so that narrows things down quite a bit, but that switch should only turn on during specific events. I'm guessing what happened is you left for Cumhaill with Melissa, went back to the Estate, and said Yes when she asked about walking around, which flipped that switch with you on the wrong side of the gate. Going into any of the buildings in Cumhaill at that point would cause the bug to lock you inside the building because that switch is on, it's not specific to the storehouse (and you're correct in thinking there's nothing to do there).
If that's accurate to what you were doing, that's super easy to fix (and is now fixed for v0.5.1). If that's not accurate, please let me know what you were doing just before this so I can narrow my search down further. I couldn't find anything else that would flip the switch on that doesn't also force the switch to turn off before you can go anywhere.
For now, attached is a fixed version of your save. As a thank you, I went ahead and got Trophy 1 for you, got you the bonus equipment out of the Freeze version of the garden maze, and left you next to the location of Trophy 3. If the bug occurs again, leave the Estate, make sure you select "No" when Melissa asks about walking around, and go over to the extreme left. Her location will also be bugged out, so she'll be hiding behind a tree in the bottom left corner of the map, and you can choose "Leave" then "Yes" when talking to her to turn the switch back off.