PathFollow broken when changing Offset using C#

[tobiasleissner]

Godot version

3.4 beta 4 mono

System information

macOS Big Sur 11.5.2, Apple M1

Issue description

Changing the Offset of a PathFollow node should lead to moving children nodes. This works when using GDScript, but the children stay at the same global world location when using C#.

This works in Godot 3.3.3, but doesn't work in Godot 3.4 beta 4, so it's a Godot 3.4 specific issue.

Steps to reproduce

1. Create a Path
2. Create a PathFollow node as child
3. Create a KinematicBody (3D) as a child of PathFollow, add a simple box mesh
4. Add a script to PathFollow in _PhysicsProcess
5. Change the offset according the delta time (change over time, specific algorithm doesn't matter)
6. Start game

In GDScript, everything works fine. Global transform of children of PathFollow nodes change accordingly.
In C#, the child nodes of PathFollow do not move. Using the Remote view of the debugger shows what happens:
PathFollow moves to the left, while the child nodes move the same amount to the right.

This works in Godot 3.3.3, so this seems to be a 3.4 beta 4 specific issue.

Minimal reproduction project

Sample GDScript for PathFollow

func _physics_process(delta):
	t += delta
	var new_offset = t * speed
	
	if new_offset > length:
		t = 0

	self.offset = new_offset

[akien-mga]

Related to #50986 / #51357, CC @raulsntos.

[raulsntos]

@akien-mga Those PRs change the C++ code so it would modify the behavior for both GDScript and C#, also C# doesn't have a custom implementation of PathFollow it just makes native calls to the C++ code so it should behave the same way GDScript does.

---

@tobiasleissner I could not reproduce this issue in v3.4.beta4.mono.official [6a058cb] with this minimal project created following your instructions:
path_test.zip

All I can think of is maybe the code you are using in C# is different to the GDScript version? Could you provide a minimal reproduction project with the C# code so I can take a look?

[akien-mga]

Ah I missed that this mentioned a C# specific issue, @Chaosus' label was correct then :)

[tobiasleissner]

I had a project with this exact behavior. However, after I deleted the nodes and recreated them, added the scripts, it worked. I cannot get back to the previous version.
I cannot reproduce it anymore.

This issue can be closed then. If it happens again within my project, I will attach the project file and reopen the issue.
Thanks for taking a look at it anyways.