Got a strange issue with outlook (Seamless published Citrix app) randomly and intermittently not opening all other citrix apps on the same server open fine there is no errors from the app and nothing in the event logs about add-ins crashing or the application hanging or crashing and when you check task manager the outlook.exe process is running in the session and not hung. We are using O365 with cached mode turned on with the outlook .ost in the Fslogix O365 container which is mounted in the affected session and no errors in the ODFC log file. If you kill the Outlook process and relaunch its fine or if you log off and log back on and hit a different server it then opens fine. I have ran a SARA diag report and no issues found and killed the outlook profile and outlook .ost in the ODFC fslogix container and still get same issue. Annoyingly its intermittent and not re producible but the helpdesk get about 20 calls a days about it all from random users. I sent a questionnaire out if they had shared mailboxes / shared calendars / large mailboxes / CWA versions / Connecting from home or office / Custom views in outlook and there is no common theme to the issue