Steps to reproduce:

1. Create a new project using 3D URP template
2. Create a new UI Document (Assets > Create > UI Toolkit > UI Document)
3. Open the .uxml file in UI Builder
4. Add a Visual Element to the Hierarchy
5. In the Inspector, navigate to the Text > Text Effects > Shadow foldout
6. Enter any value into the "Offset" property and "Blur Radius" property
7. Click Ctrl+S/Command+S shortcut to save
8. Observe the Console

Actual results: "Blur Radius" value resets to previous value and "IndexOutOfRangeException: Index was outside the bounds of the array." error is thrown

Expected results: "Blur Radius" value remains as entered and no errors are thrown

Reproducible with versions: 6000.0.0b12, 6000.0.72f1, 6000.3.13f1, 6000.4.3f1, 6000.5.0b4, 6000.6.0a3

Not reproducible with versions: 6000.0.0b11

Tested on (OS): macOS 26.4, Ubuntu 24.04

Notes:

• In versions before regression no error is thrown but the value is still reverted to the previous one, so the regression in this case is only the error
• Does not reproduce when saving via File > Save
• Reproduces if any additional value is change in addition to modifying the "Blur Radius"