Bug in the dialogues in the scene with Sangsue after using lockpicks on the chest.
She left, then a little white line appeared instead of the dialog box, then her art appeared again.
A screenshot of the outcome here:
Apparently, when this bug happens it affects every dialog box afterwards.
Even in battles:
Does it persist through saving/loading?
A save made before the bug will be free of it. No problem when loading.
But saving the game after the bug will save the bug in that data as well. No problem when loading other data, though.