The Delegates settings were not saved correctly. Cannot activate free/busy information

Got this error message today when trying to update some delegates settings:

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Microsoft Office Outlook
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The Delegates settings were not saved correctly. Cannot activate free/busy information.
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OK
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To fix the issue I needed to use MFCMAPI tool. Just follow below instructions and all should work fine:

1. Start the MfcMapi.exe
2. On MFCMAPI x86 Build window, click OK
3. Go to Session > Logon and Display Store Table
4. Choose the user profile (if the computer has more than one)
5. Double-click the Mailbox - username store
6. In the navigation pane, click Root Container.
7. In the details pane, right-click PR_FREEBUSY_ENTRYIDS, click Delete Property, and then click OK.
8. In the navigation pane, expand Root Container, expand Top of Information Store, and then clickInbox.
9. In the details pane, right-click PR_FREEBUSY_ENTRYIDS, click Delete Property, and then click OK.
10. Close MFCMAPI
11. Click Start, click Run, type outlook.exe /cleanfreebusy, and then press ENTER.