RE: "Record Updated" Tile
Hi Fabiola,
As documentation said, the tile is used to monitor records and then find the contact associated with monitored record.
https://docs.microsoft.com/en-us/dynamics365/marketing/customer-journey-tiles-reference#record-updated
The lead example it shared is a good case for us to understand how it works.
In your setting, actually you are monitoring master contact instead of contact itself.
In Customization > Contact > Fields, we can find that the field is used to identify master contact for merge.

If we didn't perform merge operation between two contacts, then the field shall be null, thus your customer journey didn't run.
I have run a customer journey which contained "Record updated" tile successfully, you could take my steps as reference:
1. Set a contact as primary contact of an account.

2. If we change name of an account, then send a notification email to its primary contact.

3. Result

In addition, we should notice that such customer journey is still not the recurring, it will only send email to contact once. (If we change account name again or more times, email will no longer be sent.)
Regards,
Clofly