\[2D]\[URP] URP Converter does not upgrade material of PSB characters to Sprite-Lit-Default

Repro steps:
- Observe both Square and Fei_Cel_Group in scene have Sprites-Default Material
- In Project Settings > Graphics > Scriptable Rendere Settings, add in New Universal Render Pipeline Asset
- Open Window > Rendering > Render Pipeline Converter
- On "Convert Built-in to 2D URP" dropdown, select "Material and Material Reference Upgrade" checkbox, click on Initialize Converters button and click "Convert Assets" with SampleScene checked
- Observe in scene, Square has Sprite-Lit-Default material but child sprites in Fei_Cel_Group still has Sprites-Default material

Expected result: All child sprites in Fei_Cel_Group should upgrade to Sprite-Lit-Default material
Actual result: All child sprites in Fei_Cel_Group remain as Sprites-Default material

Note:
- Reimporting or deleting and re-adding psb asset fixes issue
- Does not occur with 2D URP template, psb character correctly imports with Sprite-Lit-Default material as default

Reproducible on : 2022.3.9f1, 2023.1.12f1, 2023.2.0b7, 2023.3.0a3