During pipe creation, a phenomenon has been observed where, after adding or deleting components, only the fitting parts (such as elbows or cross joints) remain by themselves.

If a 3D curve remains, the fittings can be deleted.

If no 3D curve remains and only the fitting part is left, the part cannot be deleted.

Delete the entire piping system, or

Suppress the parts that cannot be deleted.

(Investigation and correction are currently in progress.)