In sometimes the filter option in get outlook mail message activity was not working. The expression you have provided is correct but the function is not working properly.
There is other way to check the condition of the mail,
→ Use get outlook mail message activity to retrieve all mails from Outlook it stored all details in List<MailMessage>
datatype variable.
→ After get outlook use for each activity to iterate mails in collection variable.
→ Inside for each insert if condition to check the sender mail address, if the condition gets true insert the activities in then block among your process if condition is false it will go to else block.
currentItem.SenderEmailAddress.Equals("xyz@abc.com")
Check the below workflow for better understanding,
Hope it helps!!