Q Light Controller+

Case:
You have a scene with a moving head setting for only pan. Tilt channel not active.
Set in simple desk the tilt channel.
Save to the existing scene with the tilt channel selected.
Result: In the scene, the tilt channel is not activated, and the value is not stored.

Analyse: Not active channels of a already present fixture in a scene are not set active and stored via dump.

Is this a mend to be behavior? Or a bug?

Don't use Simple Desk for that purpose. You can easily create a through scene for that.
Go to functions + create a scene. Add your fixture. Only select the Pan channel square. Set value. Done.
When you recall this scene elsewhere (through a button on VC f.i.) you can call this scene again, and it will use the earlier programmed values.

If you need to create a scene for everything that is running: use the DMX-Dump button in the upper right corner. Now you can select what channels have to be included in the dumped scene. https://docs.qlcplus.org/v4/main-window/dmx-dump