Mercurius-Nostradamus-Enigma-first-riddle-lady-couch

Climb up to the first floor of the house (that is 2nd floor for all you US folk out there) and you will see a painting of a lady and a couch next to her.
Climb up to the first floor of the house (that is 2nd floor for all you US folk out there) and you will see a painting of a lady and a couch next to her.
For some reason mercurius first riddle won’t let me interact with the rune. Eagle vision spots it, but no interaction appears. I’ve got all other riddles complete. Please help?
For anyone encountering the same issue Brion (and I) did, you have to go back downstairs and interact with the symbol to start the riddle again. That fixed it for me.