Received from/sent to [domain] rules intermittently not working/firing

I created two rules in Outlook 2010 to categorise mail from certain domains however this is intermittently not working.

Here's my inbound rule:
"Apply this rule after the message arrives
from domain.co.uk
assign it to the category category"

Here's my outbound rule:
"Apply this rule after I send the message
sent to domain.co.uk
assign it to the category category"

Is there something I'm missing here or is this a bug?  Even when I re-run the rules it never picks up the emails that didn't fire first time so at least it's consistent.

BTW our email is hosted on MS 365 Exchange.