Based on comment on YouTube and GitHub by @n30s4m:
I use a Wacom Intuos CTL-4100 and I was unable to see the cursor when I tried to operate the pen. To solve it, I went into the pen settings in the pen program and changed some settings.
- I added the Obsidian program.
- In options, pen button mode, I chose click and tap.
- I enabled pressure compatibility.
Now, i see the pointer.