Unions causing climbing/collisions issue in-game

Hi all, a few hours ago I got reports of players not being able to climb up stairs (like there’s an invisible block). This has never happened before and I hadn’t changed anything. Sure enough, in-game I’m unable to climb up stairs. However it works absolutely fine in studio. I’m sure something has been changed in the last 12/24 hours for this to happen!


In studio:


EDIT: Discovered some more information.

I deleted this Union here and it now works fine:

It seems as if a new roblox release increased the hitbox size of unions or something as the hitbox was esentially like this:

Union settings:

Aside from the bug, a good practice would be to place some wedge (in your case a tilted brick would make more sense), and disable collisions on the stairs themselves.
That way the character doesn’t have to analyze how stairs’ steps work, and instead it’s just climbing a smooth surface. It’s very useful if you want to avoid any difficulties similar to what you’ve shown in the OP.

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Yeah, thank you! In terms of the bug it seems something to do with union hitboxes/collision detection has been broken!

You could try checking how the collision mesh looks by enabling ShowDecompositionGeometry property in settings (you can also use this plugin)

Well that’s the thing; it looks fine but in-game the collision hitbox is clearly not that!

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