I don't know about programmable keyboards, but my old keyboard, the Microsoft Bluetooth Mobile Keyboard 6000, could combine Fn with shift at least. I finally got the software installed, remapped PgUp and PgDn to Home and End, and then the idea was then to remap so Fn+End would be PgDn, but that didn't work. Could not find any place to remap what the Fn key does. So now I've lost PgUp/PgDn.
The Fn key is used with other keys for certain commands/functions, the Fn key cannot be reassigned.
Reset your keyboard and reassign a Ctrl and Alt key as Home and End.
I'm also a software developer in the same position with this keyboard
shift + end / home to select a line are super common combinations for programming and used constantly
this feels like a bug where there is a conflict between the shift and fn key and I am guessing it might only be rectifiable in firmware
is there anyway this can be raised a bug with the dept who support firmware for this keyboard
shift and fn + combination should not be conflicting like this
remapping is fine but this is a work around not a solution