Might just be a rotational issue. Try grabbing the Wedges and Moving them up (or look through the baseplate. You may see that you have to rotate 2 of the axes by 90 degrees so the wedges align.
I’ve seen other posts about doing this before. Most mention the Gapfill plugin as a reference for how it works.
The brilliant guru @EgoMoose wrote this article explaining how to create any triangle using no more than 2 WedgeParts:
Articles/3d triangles/3D triangles.md at master · EgoMoose/Articles · GitHub