Spline Loop Segments Won't Connect Despite Same Tangents

So I’ve been trying to get a loop out of my spline segment for a while now, as I’m designing a racing game and want to create a nice loop for drivers to go around without having to make multiple splines to do it. And to be clear, this is a vertical loop, not a horizontal one, essentially they’re going upside down and around.

The first problem I encountered was getting the spline to even allow that in the first place without twisting at both ends where the spline rotation flips, creating very bad twisting at those sections. I researched many different answers for this as it’s a common problem, but each solution is saying a different answer. I tried everything I could find and only one solution actually came up and worked…slightly.

Many people say changing the default up direction, the spline up dir, or using the spline up dir at spline point was the answer, but in truth the only one that managed to work in my system was the RotateVectorAroundAxis combined with Set Spline Up Dir. This finally set each segment of my spline facing the correct direction. Unfortunately it now has another problem, one I can’t even begin to figure out because I can’t figure out what’s going wrong.

As you can see from the image, each segment is facing the correct orientation, but the ends are not curving to match each other. I checked and each of the segment tangents are indeed matching. The start of one matches the end of the previous. From what I can tell, the matching of the up vector for the start and end tangents of each section is causing each one to not deform at all, thus creating the stair like effect here.

For all my research and debugging, I cannot find the specific cause of this issue. So here’s what I know:

My system breaks down the spline distance into segments, in this case 338 of them of similar size.
The Spline Up Dir is set from the start tangent being rotated around the Y axis -90 degrees and then applied to that specific spline mesh component, which I’m assuming is the segments themselves. I’ve tried doing this with the end tangent and a midpoint tangent and nothing changes.
The positions and tangents from the start and end are calculated as expected for each spline mesh component and applied at the very end. I’ve tried doing this in different orders and nothing changes.
If I attempt to use the Spline Point Up Dir node, it simply reverts back to the bad twists.
Changing the Spline Point Tangents appears to do nothing except mess it up.

Any help on this issue and examples of working loops would be just awesome, though be warned I’ve tried many different solutions found on this site and most have not worked, perhaps it’s a different system of splitting things up, different versions, I don’t know, but I might have already tried solutions you may suggest. Otherwise, any insight to this problem would be greatly appreciated.

Here are the screenshots of my full spline system from start to finish, it’s not too complicated.

The scale value is 1, so the section length ends up just being 100. The spline length is: 33807.0892

Is it safe to assume the mesh is dense enough to deform?

Yes, the mesh has a lot of vertices in every axis. The actual road looks like a square, I’d say about 5-7 of those “planks” make up one full mesh. It also deforms quite nicely when I use other methods, they just twist the incorrect way.