Hi Ben,
May I know how you added the other two Office 365 accounts in your Outlook? Added as separate accounts via File > Add Account, or as additional mailboxes via Account Settings > More Settings > Advanced > Add?
Do the conditional formatting rules work if we create separate Outlook profiles for these accounts?
May I know what rules you created and how you created the rules so that we may try testing it in our environment to see the result?
Regards,
Steve Fan
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