I made a few attempts going different ways.
My scenario notes, I wanted to be thorough with what I tested and noted down incase I missed a case...

user2 shared full access to user1. All calendars were blank before connecting to Outlook. Shares were setup before connecting Outlook. No actions were performed in Outlook in my testing except switching to calendar view and connecting to User2's calendar from Outlook account settings. Every event came from webmail.

Outlook logged in as user2, Webmail logged in as user1, added calendar event from user1.

Outlook logged in as user2, Webmail logged in as user2, added calendar event from user2.

Outlook logged in as user1, Webmail logged in as user1, added calendar event from user1.
Outlook logged in as user1, Webmail logged in as user2, added calendar event from user2.

In all cases the event created from webmail showed up in Outlook automatically while I was sitting in calendar view, so that I did not have to click anything to see the new event. All events came in as quickly as ~4 seconds and some took about ~20 seconds, this delay is completely up to Outlook, we send outlook a notification within a second or two of a change.

If you got a reproducible scenario on a test environment I can try these same steps I did in your environment to ensure I'm replicating correctly that would also rule out anything we have in our internal builds.

Matt

How are you connecting User 2 to User 1 calendar "from Outlook account settings"?

I'm simply, as User 1, opening user2 shared calendar in Outlook.

I'm running my testing in a VM - not sure how easy it is to share other than a remote session to my PC?

Ciaran

This is how I did the share, there is another method which intermittently works. I checked our bug list and I do see this on there, I believe that bug is waiting for another sharing issue of ours to get resolved. We have some read-only problems in MAPI right now, which is why they are disabled and can't be seen. I may take another stab at it this week once we get other issues ironed out. I'll keep you updated on it.

“Open Shared Calendar” button in Outlook doesn't always work as expected.
https://portal.smartertools.com/community/a92601/smartermail-public-beta.aspx

"I'm running my testing in a VM - not sure how easy it is to share other than a remote session to my PC?"
I use ShareX for GIF/video recording on my desktop. Allows you to blur areas, capture certain areas. In Teams I use mp4, on web I can record as GIF. It works pretty well minus the DPI rendering issue, the mouse doesn't line up with video. To be fair I'm out of date on it and I've got a funky DPI setup.

Ahh ok, understood.

I'm going to reinstall the environment and repeat things using your method to see if that makes a difference in my setup.

Probably going to be tomorrow as it's nearly midnight here in the UK.

Ciaran

Yeah, That works although I am seeing date/time differences between SM and Outlook. Blew away the Outlook profile and re-set it up using autodiscover.   I'll investigate more tomorrow but one step forward for me !!

Thanks for the hint - and I think the other event you referred to is one I submitted during the early BETA.