i think it has something to do with route progression. try playing through lina's route and just buying each time you complete a step. make sure to save right before.
I just got to this point, and it's still happening.
Strangely enough, earlier on I didn't have this issue, but I had to reload a save because I messed up the quest progression by talking to Anna, and since then I picked up the [Mysterious Suitcase] and now it's happening.
-- Tried it again on a save from a minute earlier in the middle of typing this lol, both buttons worked fine. Not sure what the issue is as both quicksaves were from the same interaction with Vika before and after picking up the boxes.