So I have two users, colleagues, and one of them can't see the other's calendar unless he uses the Outlook Web App to check.

It's a very strange issue. I believe the one having the issue is on 365 and the other on a standard 2013 license - I'm only 90% sure on this.

I've gone through multiple troubleshooting steps by now and have discerned that it's most likely the outlook client - so what could be causing this issue? The one who's calendar he is trying to see recently had his office reinstalled and a new license used, if that changes anything.

Thanks.

Have you checked in outlook on the calendar trying to be viewed that the permissions are set correctly?

Go to the calendar tab in outlook, Right click the calendar, Share --> Calendar Permissions.

Yeah they're both set as Reviewers with proper permissions for each other. If it helps - I can see his calendar, I can see both of their calendars - he just can't see his colleague's calendar.

I could have another fiddle with the settings - don't have a chance to right now.

I'd reinstall office but there may be a conflict with the licensing so I don't want to break it.

Do you get any errors from outlook when trying?

Is the outlook in Cache mode?

Hi,

If this user is using Outlook in Cached Exchange Mode, please switch to Online Mode to check whether this issue persists. If there's no problem in Online Mode, I suspect the issue is that the user's local cache(.ost) is not updated completely.

Browse to the user's Outlook Data File(.ost) location, rename it to .old. Outlook will generate a new one to sync when it starts next time. If the .ost file is a large one, consider to use Scanpst.exe to repair it before using a new one.

Melon Chen
TechNet Community Support

Thank you for the suggestion, please give me a little while to try this answer as both colleagues are out of the office for the rest of the week.