If a Chalk User is registered with non-English characters, Vuforia Chalk app on iOS will prematurely exit when "Start Session" is clicked.
This "Start Session" is only used by the user with HOST privilege.
#This issue is scheduled to be fixed in the upcoming release.
Device/OS : iOS (iPhone or iPad)
Vuforia Chalk version: 2.8.3
Delete a registered user and once again add a user using English characters only.A user name is cached and updating the user name doesn't fix this issue.
It's also best to Log out from Vuforia Chalk App before deleting a user. Settings > My Account > Log Out