Problem:

There is no way to filter records based on e.g. one entry in a multiple select field, one assignee out of multiple, a certain linked record out of multiple links or a substring contained in a larger string.

That's because formulas like GET_LIST(CONTAINS([Linked Record].[Assignee], "George"), [Linked Record].[Title]) return errors.

Solution:

1.

If a CONTAINS operator was available and we could write GET_LIST([Linked Record].[Assignee] CONTAINS "George"), [Linked Record].[Title]) it would really expand what filtering can be done in formulas

2.

If a sub-array of the individual items involved could be accessed it would allow the == operator to be used. E.g.

GET_LIST([Linked Record].[Assignee].[First Name] == "George", [Linked Record].[Title])