Problem with MIDI > Merge MIDI in Loop?

Hello! I am using Cubase 14 with iMac (OS 13)

Process:
I create an instrument track and set Cycled MIDI Recording to “Mix Stacked”. I make several takes resulting in the creation of data in several lanes. I select MIDI > Merge MIDI in Loop.

The result:
A new part is created but it appears in Lane 1 superimposed over the pre-existing part in Lane 1. I can then drag this new part (without the pre-existing part) either to create a new Lane or a new Track. However, I expected this last step to happen automatically.

Have I done something wrong or is this a bug in the program?