I get an error message every time I use a custom event. I know the Steam version doesn't suffer from this.

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ERROR in
action number 1
of Destroy Event
for object evt_xxx_custom:

Variable evt_xxx_custom.sound_added(103393, -2147483648) not set before reading it.
at gml_Object_evt_xxx_custom_Destroy_0
############################################################################################
gml_Object_evt_xxx_custom_Destroy_0 (line -1)
gml_Script_draw_card (line -1)
gml_Object_evt_xxx_custom_Mouse_53