Guide

Salesforce has no assignment rules for opportunities.

Assignment rules exist for leads and cases only. So when a deal ends up with the wrong owner, there is no rule to read. The owner came from one of a few places, and each can go wrong on its own.

Where a deal's owner comes from

• Conversion. Whoever converts the lead chooses the owner, and by default it is the lead's owner.
• A record-triggered flow. A flow on Opportunity that sets the owner, for example at a stage change.
• The account owner. Many teams expect a deal to follow its account.
• A routing tool, where it routes opportunities as well as leads.
• A person, changing it by hand.

What goes wrong

• Two flows both set the owner. Which one wins depends on the order they run in.
• A flow assigns to a hard-coded user. When that person leaves, deals keep going to them.
• The owner keeps changing. A flow and a person, or two automations, each overwrite the other.
• The deal and its account have different owners where they are meant to match.

Check it yourself

SELECT Id, OwnerId, Account.OwnerId FROM Opportunity WHERE IsClosed = false AND AccountId != null
SELECT OpportunityId, COUNT(Id) n FROM OpportunityFieldHistory WHERE Field = 'Owner' AND CreatedDate = LAST_N_DAYS:7 GROUP BY OpportunityId HAVING COUNT(Id) > 6

In the first, count the rows where the two owners differ. The second needs history tracking on Opportunity Owner; each owner change is written as two rows, so more than 6 rows is more than 3 changes in a week. Then, in Setup, list the active record-triggered flows on Opportunity and open every step that sets the owner.