GridMap set_cell() offset on the y-Axis, can't identify the cause

Godot Version

4.2.2

Question

I’m trying to make a Townscaper-like game using the GridMap (or rather the WFCMapGenerator plugin by pietru2004 from GitHub that extends the GridMap). Right now I’m working on removing cell_items via right mouse button pressing, which in my case means replacing the given cell_item with another (empty) one.
Raycasting works fine, the correct cell’s position is identified, translated into grid_map coordinates and passed on to a function in the plugin that sets the desired cell_item at the given position (all verified by print outs)
All works fine, except for the new cell being placed with an offset of (0, -0.5, 0) and I simply can’t fix it…

I tried to locate the problem, here is what potential causes I was able to eliminate so far:

  • cell_center.y/cell_size settings

I thought the problem might stem from incorrect cell_center or cell_size settings, so I made sure to set the cell_size and cell_center manually in the ready() function of the WFCMapGenerator nodes script and made sure to print out the resulting cell_center.y (false) and cell_size (1, 1, 1).

  • cell_center/cell_size overrides

I looked through the plugin’s scripts and the attached singletons to make sure neither cell_size nor cell_center had any override later (they do not).

  • manual adjustment

So, since it is a systematic error, I tried to fix it manually by adding (0, 0.5, 0) to the cell’s position in the set_cell() method… but the offset still remains…

  • collision form of cell_item “empty”

Since the cell I replace with is empty (= a point_mesh) I made sure it has (1, 1, 1)-BoxDhape3D attached as its collisionshape as well… so sadly that isn’t he culprit here either… (I would have been surprised by that, since that problem never showed up when auto-generating with the MapGen in editor)

I’m at a loss as to what happens here and would like your input…