I had the problem with my X45 calibrating fine in Windows 10, but in the sim the X & Y axes are stuck full to one side. I had this problem in DCS a few years ago and the same solution works here. Make sure you have the x45 legacy drivers, here’s the link from Saitek:
==============================================
First remove the USB plug for your controller from the PC.
Press and hold the Windows key on your keyboard and then press the letter R. This will open the Run box. Type regedit and then click ok.
The Registry Editor will have a list of folders on the left hand side. Go down into the following folders in order by clicking the + next to the folder name.
+CURRENT_USER +System +CurrentControlSet +Control +Media Properties +Private Properties +Direct Input
Delete any folder inside the Direct Input folder that begins VID_06A3.
Now, again with your stick unplugged, run the driver install, and follow the instructions, plugging in your stick when it tells you. Calibrate it and hopefully you will be good to go!