I'm also an FX3 owner in the UK. After updating my firmware to 4.0, I did retain the ability to switch between NTSC and PAL. It's interesting to note that your camera lost this functionality post-update.
It might depend on the regional version of the camera as I reached out to Sony about the issue, and they said they're limiting it on purpose. If your FX3 was intended for a different market (like the Japanese market, as I learned in my case), the firmware update might enforce the original regional settings, which could explain the loss of the NTSC/PAL option.
It could be worthwhile to check with other FX3 owners from various regions to see if they experienced similar issues. This could help determine if it's a widespread problem or isolated to specific regional models of the camera. We all should complain about it and urge them to take action to fix this unfair policy.
Hope this helps!
