Add a bracket which spans two staves

I want to add a bracket which spans two staves.

I am following the instructions at:
https://musescore.org/en/handbook/4/brackets

But a single-staff bracket is applied to every staff, and I cannot extend the bracket to the next staff below -- the bracket just snaps back to the single staff it was added to.

These are the two methods I am trying to use, from the above instructions link:

"Adding bracketsTo add a bracket or brace to all systems:

Click on the first measure of the staff where you want the bracket/brace to start, hold Shift and click on the measure where you want the bracket/brace to end. Click the desired bracket icon in the "Brackets" palette.

Alternatively:

Select the start measure, and click the bracket into place from the "Brackets" palette. Select the bracket, click on the adjustment handle and drag it down to the desired position. It will snap into place."

I have just updated my MuseScore to the latest v4.2.1... Can anybody tell me why these methods are not working?