Instead of the score being displayed, the message "A number is required" appears.

Here's the tricky part. This works fine and as expected for everyone, except for one player (at least that I'm aware of), using Windows.

I have found little to no information online about what could be the cause of this.
All scores are integers, which are then converted to strings for displaying in the HUD.

Any ideas? Thank you.

    zapposh It's very hard to tell anything unless having already encountered such error which looks like to be quite a tricky case as it is OS related.

    You could check the Godot source code for the message, it may help pinpoint where it comes from, the case involved and maybe get a lead.
    If you wish, I can test your game (or just the scene with the score and some test code ready to use), which looks nice by the way, I works with Godot on Win7. It could help find what is triggering this.