1.21beta crash QGIS when import a lod2, Germany, RLP, buildings in a sqlite db via wizzard

[gespiel]

Environment

Hello,
thanks for your work. We are a small town-administration and receive Lod2 Data from German Katasteramt, Rheinland-Pfalz. The Lod2 contains the 3d buildings with roofs from one of our small villages.
I tried, to load the 3d buildings in QGIS with your plugin.
Using the standard settings in the plugin wizzard, work ends with a popup, that there are faults in the "wallsurface" layer. The plugin give the advice to activate sthe "skip faults" option.
Done this, the process starts and the progressbar in the popup terminates with 100%. Then the wizard window freeze (no response), the the Mouspointer shows, that something is in process and after around 2 minutes the complete work lead in a QGIS crash.
The sqlite db is created (near 7MB). It is possible to load with your plugin the GMLAS database in QGIS, but there are no geometries in the polygon layers.
Do i something wrong?

• Plugin version: 1.21 beta
• QGIS version: 3.16.2
• Operating System: win7 and win10

Description

<-- Here write a clear and concise description of what the bug is. -->

Aplication Shema plugin crashes QGIS when load LOD2 from German Kataster, RLP.

To Reproduce

Steps to reproduce the behavior:

1. Go to '.load wizard..'
2. Click on '...complete(start)'
3. Scroll down to '....'
4. See error -->Pugin crash QGIS

Expected behavior

<-- A clear and concise description of what you expected to happen. -->

The wizzard should load the generated layers from the sqlite db in QGIS.

Additional context

<-- Add any other context about the problem here. -->
I tried to convert the same LOD2 via ogr2ogr with gmlas driver
(ogr2ogr -f SQLite tmp.sqlite GMLAS:LoD2_xxxxxxx.gml -dsco SPATILIATE=YES -nlt CONVERT_TO_LINEAR -oo EXPOSE_METADATA_LAYERS=YES ). I could load buildings, wallsuface, groundsurface and roofs from the sqlite db as layers.
The 3d map in QGIS shows the 3d-buildings, but there is a problem with the groundsurface. The buildings float about the ground.

If desired, i can give a downloadlink with dataset, screenshots and logs.

Logs

Include some logs here, in QGIS Logs panel, bottom right icon, the small bubbles.

Screenshots

<-- If applicable, add screenshots to help explain your problem. -->

[Guts]

Hello @gespiel, thanks for your interest and taking time to report.

Could you complete the steps to reproduce please? Or give us the datasets or a sample?