Flow keeps executing due to possible loop, but I don't see it

Good morning,

I created a workflow to send emails when certain actions have been completed. Basically, when an item is created, an email is sent to the next person which needs to take action, so on and so forth. I am using person/group fields for the individual.

When they finish their action, they update their item to Complete. The next person assigned will then receive an email stating an action is waiting. 

This seems to work okay but PA notifies me of 'Actions in this flow may result in an infinite trigger loop. Please ensure you add appropriate conditional checks to prevent this flow from triggering itself.'

But I am not seeing it. I have condition statements that I believe should constrain and prevent this.

Below is one that has fired multiple times (10 +) and should have only fired once after a record update.

The below example should only fire when the Source Document status = Complete, Source Document date is null and the Video Editor status equals 'Not Started'.

When those conditions are met, an email is sent to the video editor stating their actions are waiting, and using the 'Update Item' sharepoint action by ID and Title, it updates the source document date to the date time the respective status was changed to Complete. The action of it entering the Source Document date in my eyes would stop the flow from triggering again since it is not null. I don't get multiple notifications and the date time isn't changed with each run. But I still don't know why it keeps firing. 

This seems to work fine and not fire multiple times when I didn't update the item and only sent an email notification. It seems that its now only doing this due to updating the item with the date of completion. What am I do wrong? Why is it continually firing? 

Thank you for your time in advance!

Mark