The Add Spatial Join tool does not work in ArcGIS Pro 3.2 when used with in-memory feature layers that have an SQL statement applied to them.

Additional Information

Workaround

Use the Spatial Join tool, which creates an output feature class saved within a geodatabase.

A second workaround is to adjust the definition query to be something like TargetTableName.Field = value, or JoinTableName.TARGET_FID is NULL.

Definition queries are not adjusted; when a definition query is on a layer, it acts like an inner join. An additional information may be updated to the documentation.

Steps to Reproduce