PS fails at separating to objects after splitting

[SimonTil]

Version

2.3.0 & 2.4.0-Beta2

Operating system type + version

Windows 10, 64-bit

Behavior

See file (STL): Brug.zip
After splitting it at 187.5mm height, I want to put the high legs flat on the bed. One leg disappears, and got an error that a model is outside the print area.
Try it yourself:

• Split the object at 187.5mm and keep the lower part only
• Click the Split to Objects icon
• Gone

I don't know how this is possible. Probably a bug, probably just a bad model. Tried to repair through Netfabb, didn't help.
I can do it in Meshmixer or so, but this should be possible in PrusaSlicer.

[dartrax]

I confirm there is something strange. After splitting like you said:

It's not possible to reveal it by using the drop icon or modify Z.