Updating Arcade Expression to the unique value symbology of a feature layer doesn't modify the symbols and turns several symbols inaccessible.

Additional Information

Workaround

Work with LYRX

• Create and save LYRX files that are subsequently updated and applied as new objects are added and attributes are updated. 
• Use the expression, add a new row, and import symbology from the LYRX.
• Select/create a suitable symbol for the new, undefined symbol type.
• Save a new LYRX file.

Work with STYLX

• Save individual symbols to STYLX files.
• Name the symbols according to the expression, such as 'Text A2'.
• Create new symbols in Style Manager as needed.
• Apply the new expression.
• Use the Match Layer Symbology To A Style tool.

Steps to Reproduce