GASP mantle problem when upgrading a project from 5.7 to 5.8

Development Character & Animation
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1

This error doesn’t exist when you create a GASP project directly in 5.8
It occurs when you upgrade any project from 5.7 to 5.8

Repro:
Tested this with a fresh clean GASP 5.7 build and switching the engine version to 5.8 (no other files added)

Actual problem:

When the player attempts to mantle up a ledge higher than 2.75m (I know, very specific) the player:

  • never does the mantle action
  • gets stuck in flying mode
  • never returns to walking

I know that the flying mode is how character transitions during the mantle phase, to move the body from A-B, but it should return to walking once the mantle is complete.
No errors or warnings are thrown up, just mantling simply doesn’t work above 2.75m and puts the player into the flying state that you cannot escape from. All debug info about the ledge grabs (front back and dropdown) looks good.
The “LevelBlock_Traversable” actor used when trying to mantle also turns into a no-collide actor. (It’s the same actor as a working one, just been raised higher to meet the > 2.75m mantle height).

I’ve tracked down this 2.75m limit to a range set within the CHT_TraversalMontages_CMC
Increasing this value say 3.75m and all the mantles that failed previously now work again.

But this is the wrong / incorrect, since a GASP project directly created in 5.8 works with the > 2.75m range.

Has anyone else encounter this when trying to upgrade their GASP project from 5.7->5.8?
And or what could the fix be?

Thanks

2

Video of the problem.

First 2 jumps are just there to prove its working at heights < 2.75m.

At 14 seconds in, I jump to initiate the mantle, but it instantly goes into fly mode, and the traversal block goes no-collide.

The stuttering on the footsteps after is the character being in flymode, but at the exact height of the floor.

3

This sounds like a migration issue rather than a GASP 5.8 bug. Since a fresh 5.8 project works, I’d compare the upgraded project’s traversal assets/classes against a clean 5.8 GASP setup.

A few things worth trying:

  • Reopen and resave the traversal Blueprints/classes after upgrading, as old CDO/default values can sometimes persist.
  • Compare CHT_TraversalMontages_CMC and related traversal data assets with the ones from a fresh 5.8 GASP project.
  • Clear Saved, Intermediate, and Derived Data Cache, then rebuild.
  • If possible, copy the 5.8 traversal assets into the upgraded project and reapply only your custom changes.

The 2.75m limit changing the behavior is a strong hint that the mantle state machine is not completing and the character remains in the temporary flying movement mode. The increased value is a workaround, but the real fix is likely a stale migrated setting or asset value from 5.7.