5.5.1 keeps crashing when using modelling mode.

Best thing to do would be to recreate the bug while recording your screen using a program like OBS or what ever you have and posting it so people can see what is happening on your screen. With out seeing the exact thing you are doing it will be very hard for people to help you. You might also want to post the hardware you are using including the stylus or input device. All the things that create the issue.