Room calendar working hours not showing properly in Outlook

Copper Contributor

Hej guys,


Please correct me if I am being crazy but I have an issue with the working hours display when viewing a room mailbox calendar through Outlook. In OWA and the scheduling assistant it's fine.


For example, I have created a brand new room mailbox in Exchange 2016 CU4. The working hours are default at 0800 - 1700, weekdays only and PST. When viewed through Outlook the whol day is grey, when using the scheduling assistant or OWA the working hours are displayed okay.


Technically this should not be an issue as I do not block booking rooms based on working hours. But the user experience is a bit crap and it could cause support cases.


Any clues what to look for?

Thanks in advance


20 Replies

I can confim this in outlook 2016 and 2010 using exchange 2016. Before the timezone was set on the shared mailbox everything shows as working hours, after setting the timezone everything was shaded grey as off working hours. OWA shows the working hours correctly. I've never checked this in earlier versions of exchange so I don't know if this exchange or outlook consistent.


edit: after setting the timezone it only appeared all 'out of working hours' for a few minutes then worked as it should.


edit2: then it went back to all 'out of working hours' again. 

I have the same issue. Outlook 2016, Exchange Online / 2016 hybrid (room boxes are on Online)


When I restart Outlook and go to calendars working hours are showing correctly but after few seconds each calendar "refreshes" and shows gray "out of hours" for the whole day.

Same issue.  Anyone have any headway?  We are Office 365 Exchange Online for our room mailboxes.  We currently are using Office 2013 Outlook.


I am experiencing the same issue. Its inconsistent which calendar it happens to, but all day events where the user is "unavaliable" seems to trigger it for some reason. It renders and views fine in the web outlook view.

I see the same issues where I work - anyone figure out a solution to this? I've noticed it in Outlook 2013 and 2016. Primary calendar show's working hours correctly, but other shared calendars that are opened show everything as out of working hours.

I am also having this same issue. Would appreciate some assistance.



Same issue.  I can't even find the Office 365 option to change the time zone for the room.  it looks like it's in pacific time. Office 365- Outlook 2013

You will have to connect to Exchange PowerShell to see or set the working times/working time time zone.

Use Get-MailboxCalendarConfiguration and Set-MailboxCalendarConfiguration.

@neil grinnall We seem to get inconsistent regional settings when we create a resource mailbox as well.


I found I needed to configure the mailbox regional settings but also the mailbox's calendar settings too. You can use something similar to the following PowerShell to configure all room mailboxes at once:


# Add all available resource mailboxes into a variable 
$rooms = Get-Mailbox -RecipientTypeDetails RoomMailbox

# Set mailbox Timezone, Language and Date & Time formats to UK
$rooms | ForEach-Object {Set-MailboxRegionalConfiguration $_.alias -TimeZone 'GMT Standard Time' -language 'en-GB' -DateFormat 'dd/MM/yyyy' -TimeFormat 'HH:mm'}

# Update the calendar's working hours start & end time and timezone to our UK corp standard
$rooms | ForEach-Object {Set-MailboxCalendarConfiguration $_.alias -WorkingHoursTimeZone 'GMT Standard Time' -WorkingHoursStartTime '08:00:00' -WorkingHoursEndTime '18:00:00'}


@Thom McKiernanSo maybe this went without saying, but after entering these bits of data you now see the proper look in the Outlook calendar with operating hours white and off time as Grayed out?  Were your regional settings empty before you ran the set commands?  Mine currently have no data in them for timezone, language, dateformat, and timeformat.  

I have been having this issue as well - tried all the suggestions of setting/resetting timezones, working hours and regional settings. The issue only seems to happen in Outlook. OWA shows the working hours correctly, which tells me that there's nothing wrong with the calendar settings, but more with the Outlook app not displaying them correctly.

This fixed the grey out issue that due to start/end time or timezone.

Just passing through the internet and came upon this thread, you also can do it all on one line. :)


Get-Mailbox -RecipientTypeDetails RoomMailbox | Set-MailboxCalendarConfiguration -WorkingHoursTimeZone 'GMT Standard Time' -WorkingHoursStartTime '08:00:00' -WorkingHoursEndTime '18:00:00' 


@neil grinnall Maybe a little bit jump in time. Did you solve it with regional settings of mailbox? Or you digg in also in default permissions for calendar folder?

@Petr Vlk 


I noticed this today too. My time zones were wrong and I fixed it with PowerShell but Outlook still shows working hours grayed out. I am assuming it might take a bit to sync up though.

@NickTT Hi, does it works for you? Or you need also fix default permissions for calendars?

@neil grinnall Was there ever a solution for this issue? We're still seeing this today: When you add a conference room calendar to your calendar view, it briefly shows the room's working hours, then the screen refreshes and the entire days appears gray like non-working hours do.


In the Scheduling Assistant view, when scheduling a meeting, you can see the working hours and the Room Finder suggests rooms as well. The "issue" appears only in the calendar view.


Is this a training issue to get people to use the Scheduling Assistant and Room Finder instead of adding conference room calendars to their Outlook profile?

@Thom McKiernan Thanks Mate - Worked perfectly for me.

2023 and we are still having this issue hours are set for the room and when you view it changes and if you add another calendar it changes again. When will microsoft resolve this 4 years and counting. Unless smeone