Exporting selected features from a joined layer in ArcGIS Pro 2.9 generates Null values in the resulting layer's attribute table's joined fields.

Solución alternativa

Use the following workaround in ArcGIS Pro 2.9:

1. Perform the original workflow's Join step.
2. Use the Copy Features tool on the joined layer to create a new feature class copy.
3. Select by Attributes > where FID is not NULL.
4. Right-click Data > Export Features to export the features.
5. Open new layer's attribute table to export the features as expected and retains all the Join fields' data.

Pasos para reproducir