Suggestions are not provided because most attendees are not available during your working hours

"Suggestions are not provided because most attendees are not available during your working hours." is one of those Outlook messages that sends you hunting through Exchange configuration even though the root cause can be much simpler.

What the symptom looks like

While testing Room Finder, instead of getting the expected list of rooms we saw this message and no useful suggestions.

After spending far too long checking Exchange settings, room lists, and mailbox configuration, the answer turned out to be much more mundane.

The actual cause in our case

We were trying to schedule the meeting for a time that was already in the past or outside the working hours represented for that day. Once we changed the meeting to a valid future time inside the working-hours window, Room Finder started suggesting rooms again.

What to check before blaming Exchange

• Verify the meeting date is not in the past.
• Check whether the selected start and end times fall inside the organizer's configured working hours.
• Check whether the requested time also aligns with the room mailbox working-hours expectations.
• If the calendar grid is grayed out for the selected time, treat that as a clue rather than a cosmetic detail.

Why the message is confusing

The wording makes it sound like an attendee availability or room-list problem, but Outlook can show this behavior simply because the chosen meeting time is outside working hours. That is why administrators often start with the wrong layer of troubleshooting.

Current note

As of April 22, 2026, Microsoft still documents Room Finder behavior where no available rooms are shown when the meeting start or end time is outside working hours and the working-hours windows do not line up. So even though this post came from an older Exchange/Outlook environment, the core lesson still holds: check the time selection first.

Once we picked a proper day and time, the rooms showed up as expected.

Sometimes the fix really is the obvious one, but only after you stop looking for something much more complicated.