selection problems

I'm brand new to musescore, so maybe I've missed something; however, this looks like a bug in the way selection operates.

I've a score with S and A parts as voices 1 and 2 on a single staff. For reasons immaterial here, I need to make the alto part invisible for a small number of measures: the part contains quavers, rests, and slurs.

So, to make the alto part invisible, I first select the range of measures (blue box appears). I then R-click on the first note of voice 2, and choose select|more... I tick 'same voice' and 'in selection'. The relevant noteheads on voice 2 change colour to show they're selected, and the blue selection rectangle disappears.

Simple experiment: just hit ^X. Notes go completely from voice 2 (the notes are replaced directly with rests of the same lengths, the rests not being merged, but never mind that for now; slurs remain, rather unexpectedly).

Set things back to the selection just before I tried ^X, and instead of ^X, untick "visible" in the inspector. Noteheads - and only noteheads - are greyed out as "invisible": this seems inconsistent with the previous action of ^X. Stems, hooks, slurs, remain visible. In fact, to make the entire part invisible, I have to go through with ctl-click to select each and every stem, hook and slur to make them invisible.

And worse - if I R-click on a slur in voice 2, and choose again select|more, and simply pick "same voice", all slurs are selected, including those in voice 1. (The same applies to the hooks and ties as I've just found while writing this. No doubt a more general issue.)

Not at all what I expected. Is this sort of behaviour to be expected, or is it indeed a bug?

Is there any way of selecting "all objects in these measures belonging to voice N" that I should be using? The "select|more" dialogue box shows the type of object being selected, but unhandily there's no way given of choosing more than one (or changing it from within the dialogue).

TIA for any comments.

Oh yes, this is 2.0.2 running on Mint Qiana.