Unity Issue Tracker - UI Builder loses all progress or the .uxml file corrupts when entering a large value (8 digits) into properties that do now have clamped values

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Regression

UI Builder loses all progress or the .uxml file corrupts when entering a large value (8 digits) into properties that do now have clamped values

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Dec 11, 2025

Steps to reproduce:

Create a new Unity project using a 3D Universal Template
Go to Assets > Create > UI Toolkit > UI Document
Open the created .uxml in UI Builder
Add any element to the Hierarchy (e.g. Label)
In the Inspector, modify any of its properties for better change visibility (e.g. Scale, Color)
In the Inspector, expand the "Transition Animation" foldout
In the Duration property enter "10000000"
Click File > Save, in the UI Builder
Observe the UI Builder

Actual results: All made progress/changes in the UI Builder are lost and reset to default

Expected results: All fields should have clamped values and not allow such value to be saved

Reproducible with versions: 2023.1.0b1, 6000.0.64f1, 6000.2.15f1, 6000.3.1f1, 6000.4.0b1, 6000.5.0a3

Tested on (OS): Windows 11, macOS 26.1 (M1 Pro)

Notes:

The issue is reproducible in fields under "Filter", "Transition Animation" and "Transform" foldouts (possibly others as well)
In 6000.2.15f1 version and below the .uxml file gets corrupted, while in 6000.3.2f1 and above, just the progress resets