See Screenshot. We are looking at the relationship between two tables, and there is a setting that effects how filtration works. REF: https://community.powerbi.com/t5/Desktop/cross-filtering/td-p/140592
For some reason, Both is not the default.
Any reason why you would not want it to be both?
With bidirectional filters, it's easy to create ambiguous relationships and/or multiple filter paths between tables. They certainly have their uses but can introduce unnecessary complexity.
I'd encourage you to check out the discussion on this topic here:
Is Bidirectional filtering really that bad?
This discussion also references the follwing SQL BI article by Alberto Ferrari:
