Emoji compare stuck if proceeded by the hydrogen client first

[hahahahacker2009]

Describe the bug
Emoji compare stuck if proceeded by the hydrogen client first
Two clients see a spinning circle and start buttons disappear.
If the element client proceed verification before the hydrogen client, emoji verification works as normal

To Reproduce
hydrogen client login, enable cross signing
element client start verification
hydrogen client accept verification, two client now on the screen show "Compare unique emoji"
The hydrogen client click "Proceed" before the element client, and two clients see the spinning circle

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):
Chrome