A Rule like this should work on new unread messages as they arrive in your Inbox:
Of course your Rule may also have additional arguments, but without seeing it, it is difficult to make any suggestion.
If you want to give screenshots of your Rules, you can send them to me by clicking on my name and selecting Message, if you don’t want to post them publically.
I made feature request that eM Client should also have option to start rule on messages that are downloaded/received, but already marked as read in second email client / webclient. It may be related or not, but if email is downloaded with read flag already set, rules just ignore that email. For some reason “after message has been received” means “after unread mesage has been received”.
Messages can never be received as read, so all new messages are unread.
But yes, @homeap, Rules only apply to new unread messages as they arrive in your Inbox. Some messages that have been affected by server-side filters, so those moved to other folders, or marked as read, will not be affected automatically by eM Client Rules.