RichTextLabel fails to update image region when using RichTextLabel.update_image()

[tanuki-billie]

Tested versions

• Reproducible in: v4.4.beta2.official [a013481], v4.3.stable.official [77dcf97]

System information

Godot v4.3.stable - Nobara Linux 41 (KDE Plasma) - Wayland - GLES3 (Compatibility) - AMD Radeon RX 580 Series (radeonsi, polaris10, LLVM 19.1.5, DRM 3.59, 6.12.11-204.nobara.fc41.x86_64) - AMD Ryzen 5 2600 Six-Core Processor (12 Threads)

Issue description

When adding an image to a RichTextLabel via add_image(), its image region cannot be updated via update_image() when using UPDATE_REGION. The image receives no changes.

Steps to reproduce

With MRP:

1. Run project
2. Witness as the image's region fails to be updated

Without MRP:

1. Create a RichTextLabel
2. Add an image to the label using RichTextLabel.add_image()
3. Update said image using RichTextLabel.update_image(), ensuring that UPDATE_REGION is set in the mask param
4. Witness as the image's region fails to be updated

Minimal reproduction project (MRP)

4.3: rtl_update_image_mrp_4.3.zip

4.4b2: rtl_update_image_mrp_4.4b2.zip