I'm guessing that setting the object as walkable, that it was preventing it from reaching the destination & likely cancelling out the immediate interaction action(s).
I never used the object walkable option. But I did a quick test with an existing project and ticking the box did not work as intended:
If a position is set, the character walked to the set position, not the clicked position (both inside the walkable area and inside the object area). Action got executed.
When I deleted the position, the character walked to the upper left corner, not the clicked position. But the action (still execute at destination) was executed.
Immediate actions work in both cases.
Edit: In the new Visionaire version either the deleting of positions or the aligning is a bit broken, I guess. Someone mentioned an aligning problem before.
When I created a new object with no position, the character would walk to the left upper corner again, but the action was not executed.
Same with immediate action - walking to upper left corner, no action.