The X1C is only supported in our V5 release. There were many software changes in that release specifically to work better with high speed printers like Bambu or other Klipper based printers. We don't have the same features available in V4.
If you need any help configuring the X1C with V5, feel free to contact our team directly at the link below:
https://www.simplify3d.com/contact-us/