I've been through this and it was very frustrating.
To all ROM Devs:
Atleast check your build.prop before implementing it.
Solution:
I found that in most ROMs' build.prop, 'ro.sys.usb.charging.only' was set to 'yes'.
change it to 'no' and it will give the option for mass storage.
All it took was one glance at build.prop.
Hit Thanks and give proper credits if you gonna use this.
To all ROM Devs:
Atleast check your build.prop before implementing it.
Solution:
I found that in most ROMs' build.prop, 'ro.sys.usb.charging.only' was set to 'yes'.
change it to 'no' and it will give the option for mass storage.
All it took was one glance at build.prop.
Hit Thanks and give proper credits if you gonna use this.