Online count not updating after new author assign

[michael-kozinets]

To Reproduce
I have created new Group Pad with API:
createGroupIfNotExistsFor -> groupMapper="group1"
createAuthorIfNotExistsFor -> name="author1", authorMapper="a1"
createGroupPad
createSession
open iframe with returned sessionID in browser 1 and see online users count = 1.

Then I did the same actions for the second author:
createGroupIfNotExistsFor -> groupMapper="group1"
createAuthorIfNotExistsFor -> name="author2", authorMapper="a2"
createGroupPad
createSession
open iframe with returned sessionID in browser 2 and see online users count = 1 (and online users count = 2 in browser 1 in the same time)

Expected behavior
To see online users count = 2 in both browsers

Server (please complete the following information):

• Etherpad version: 1.9.7
• Browsers: chrome and firefox