How to apply transitions to the current scene behind a Ren'Py choice menu
Here is example code to apply the blur transform to the master
layer when a choice menu is displayed, along with applying a fade-in and fade-out effect of the choice items.
This was tested on Ren'Py 7.4.0.1167.
@SlayerA259, could be a number of things - not really possible to say without seeing your actual code. Could also be that this requires Ren'Py 7.4, and you're still on 7.3.