Ha, that's really strange. The only thing I can think of is - if you investigate the room before you know you need a mother's blessing (so before you examine the statues or before Helga translates the symbols for you), the player character doesn't ask Masha for her blessing after the flashback cutscene. You then have to talk to her again once you know what you need from her, and she will give you her blessing.
If this doesn't work, then it's probably really a bug. Let me know how it played out, thanks for reporting!