VU meter rings sometimes don't animate

[dbkr]

Describe the bug
In testing another bug, I'm currently getting media successfully but the VU meter rings on the receiver are not moving.

[dbkr]

I think this is reproducible by leaving a call and then re-entering (ie. press the back button)

[dbkr]

I think matrix-org/matrix-js-sdk#2484 has fixed this