Thanks all for your help. I randomly found the solution for this on YouTube in the comments of a video review for Sound BlasterX G1.
This is the comment:
The Creative Sound BlasterX G1 from the factory is held back thanks to a pre-installed audio-profile which is suitable for consoles too. Which means if you use it on a PC/Laptop/etc it will only deliver up to max. 48khz & 16bit. Theres no option to change that inside the Control-Software "BlasterX Acoustic Engine Pro", and you will need an additional software from Creative called "X-Plus Configurator". There you can switch between a couple of audio-profiles, and you should change it from PS4-Generic to just "Generic". After you updated the G1 you can finally use its max capabilities with 96khz & 24bit. If you wanna use it on console's again, just switch the profile back. PS: Excellent Soundcard when unleashed, for its price.