Hi Mark,
May I collect some information to troubleshoot this issue?
1. You have tried to delete and re-create the rule. This is really a good step to troubleshoot this issue. Does this problem persist after doing this?
2. Have you check if other users in your organization have the same issue? This will help us narrow down this issue.
3. Are you the administrator of your organization? If so, you can use PowerShell to check the Inbox rules:
a. Connect PowerShell to Exchange Online: help.outlook.com/.../cc952755.aspx
b. Use the following commands to check the Inbox rules, are they all enabled?
Get-InboxRule -Mailbox MailboxName
Note: Replace MailboxName with the name of your mailbox.
Thanks,
Young Yang