Office 365, shared mailbox says 3 unread messages but they aren't visible

A user has, in addition to their own mailbox, a shared mailbox in Outlook 2016. It says there are 3 unread emails, but none are visible. At the bottom of the pane it says "displaying messages newer than 12 months". Maybe the 3 are older than 12 months? But I don't see anywhere to adjust the shared mailbox settings so we can see older than 12 months. Where is that adjustment made?
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timgreen7077Exchange EngineerCommented:
displaying message newer than 12 months should be a link you can click and it should show more mail. this action has to do with the cache mode settings of the user mailbox. click that link and see if it shows more content.
BobbyAuthor Commented:
It's not a link, just grey text. I tried it.
if you are operating in cache mode, you need to go into your mail settings for the account(s) and slide the offline settings to All (see attached)

also did you, in Outlook, click the UnRead button to the right of All?

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Vasil Michev (MVP)Commented:
Or you can just check via OWA, as Outlook can sometimes show funny things because of local cache corruption.
BobbyAuthor Commented:
Yesterday I went into her account settings and set the slider to All, and let it populate overnight, but the shared mailbox still shows those 3 unreads and they are nowhere to be found. It no longer, however, just displays the last 12 months so the slider setting DID take effect, but I still have no idea why it shows 3 unread messages. Ive expanded every folder etc, they just arent to be seen.
BobbyAuthor Commented:
Anyway, it was probably an old folder that didn't completely download properly when we first set up that shared mailbox... in any case, those emails have now been deemed not important because everything is accounted for. So, I just made the inbox "mark all as read".
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