Often after rendering a video, the mouse pointer is still disabled. I have to press Esc and T to get it back. I've had issues where the pointer would still be gone after I came back to the main menu, I had to move the mouse around enough to see the Replay Viewer button highlight, click it and open a replay so that I could bring the pointer back with T.

If it's possible, would be good to always reset the mouse pointer to be visible on exiting.

MC version would be important (I'm guessing 1.12.2?) mouse pointer management has changed a few times over the years (especially with 1.13).

after rendering a video
after I came back to the main menu

Are those two distinct issues or does the former always precede the latter?

Would be important to list all the occasions where this happens to you cause I can't tell because with my setup applications aren't allowed to hide my mouse pointer, so during development I wouldn't notice this kind of issue.

I've mostly been playing 1.12 but if possible it would be good to just always "reset" it...

I meant when I came back to the main menu after rendering a video. Now I always check after rendering a video, but since the mouse is centered at that point and close to the "Quit Replay" button I've often just accidentally hovered over the button, seen it get highlighted and clicked.

There are other occasions in the Replay Viewer itself (e.g. I've seen it disappear when the player is teleported while previewing a replay) but those aren't too bad as you're always toggling between camera and mouse anyway.

I also had RM crash on a render queue (NPE but it turned out the split recording I had was not good to work with) and then there wouldn't be a cursor but I don't expect you can catch all of those.