ActorOnClicked not working - Please Help!

Hi there, this is our first Unreal project, it is for cultural heritage.
We work on a very famous hall, called “Hall of the Months” inside a renaissance palace in Ferrara - Italy.

Users are supposed to explore the hall and when they gets near to a fresco painting and look at it, they can click it and access a menu and see some videos about the fresco.
(see the scene view and gameplay attachments)


We have a blueprint on the First Person Character (see attachment) that performs a LineTrace and returns the name of the object looked (oggetto guardato variable).


On every painting there is a rollover (the luminous frames you can see) that lights up when the user step on a box collider and looks towards the painting.
When the 2 conditions are true (looktest and step test) the rollover is activated and if user clicks, the menu should open.

Unfortunately, this happens only sometimes randomly (??)
It seems that if the player gets very close to the wall, it works better and every time you click.
When player is more distant from the wall, it works only sometimes.

Any idea will be appreciated,
sorry if its not clear, we can give more info, and a huge thank you to anyone that will help!