I understand this is not Microsoft Support. You ask. I will answer.
To be honest, since I've had the 'new' pen, it has never worked 100%. There are days where it works. Then a few days later it doesn't. So that's why I said it's not 100% reliable. One day I took it to a meeting with a client, took it out and it wouldn't write. Now I have no way to take down notes. I had to borrow a notebook and pen. How embarrassing.
Yesterday, it wrote fine on (docked and undocked). I scribbled some lines and it didn't miss a beat. So at 5pm, I closed the lid, put it in my bag and went home where it stayed until the next morning. I unpacked, turned on (off sleep) and checked emails etc. Then went to Note and grabbed the pen to take some notes. Nope. Worked yesterday. Doesn't work today. Nothing would write.
Touch functions works fine. I can close out of One Note just fine by using my fingers. One thing I noticed (and might be why I have this problem) just now. I removed the battery from the pen. But in the Settings, it still says "Surface Pen paired..and at 93%". How's that possible? Unless the laptop doesn't provide live real time data. The Pen should be disconnected because the battery was removed.