John
Not sure what to tell you to help you with your denial that X1 is in fact messed up in many ways John.
Perhaps so. However not everything in it is. It helps no one to consistently offer some vague notion about it not being workable in a particular way if you have no evidence that is so. If you don't know how something is done in this new version please don't attribute that to some bug that is due solely to your bias against it.
Yes it has problems but the real ones are not helped by creating imagined ones. It puts us all at a disadvantage in finding what works and what doesn't.
I use the split and nudge actions all the time. Never a problem with splitting/nudging - typically I like to use the alt/left mouse click for splitting.
A couple of things I keep in mind when splitting or nudging is whether to use/or don't use snap to... depending on the material where it needs to land. Another is, if I know I need to move a portion of the clip, I make room for the "nudging" by slip editing for some space to work in.
I would never be absolute around who is/is not having problems. However, like FBB said, I must have gotten a different version of Sonar...
I have a simple thought for having a well oiled sonar or any daw session. Keep my computer lean as possible (mine doubles for another business) and use or get a reliable audio device with steady/stable drivers. I've had a delta1010 for the past 10years that just keeps in ticking. My eye is on something RME in the future or perhaps Roland's Octa-Capture when the delta has run its' course.