Greetings Clooneym,
Lets check to see which mode the camera is in when shooting in the SCN mode. The flash may not be available if the camera is set to a specific sub-mode. For example, if the camera is set to shooting a portrait in the SCN mode, but the background blur option is not set to "AUTO" then the flash will not fire.
Page 63 and forward in the user guide will provide us with information of each mode within the SCN mode and any limitations that may be available with each.
https://gdlp01.c-wss.com/gds/8/0300035728/05/psg7x-mk3-ug5-en.pdf
