Tested versions

• Reproducible in 4.3-dev6
• Not reproducible in 4.2.1-stable

System information

Windows 10.0.22631 - Vulkan (Forward+) - dedicated AMD Radeon RX 6700S (Advanced Micro Devices, Inc.; 31.0.24031.5001) - AMD Ryzen 9 6900HS with Radeon Graphics (16 Threads)

Issue description

Updating a project from 4.2.1 to 4.3-dev6 a font broke, showing every character as "missing glyphs" with hex codes. It was png imported as FontData.

Changing the settings and re-importing didn't seem to fix it until I reassinged the png to the LabelSettings resource. After extracting the file to an MRP it seems reimporting doesn't always update the resource in open scenes. This didn't occur in 4.2.1

As regards the font breaking after upgrading from 4.2.1 to 4.3-dev6, I still haven't manage to reproduce that.

Steps to reproduce

• Open the attached mrp with Godot 4.3-dev6
• Open control.tscn
• In the Filesystem dock, select "TimerNumbers_10.png"
• Go to the Import tab
• Change "columns" from 10 to 15 and click on "Reimport". The text displayed in the 2D viewport should now look garbled (as expected)
• Change "columns" back to 10 and click on "Reimport".
  Expected: The text looks correct again
  Actual: No change.
  Workaround: You need to reopen the scene or reassing the png to LabelSettings for the changes to display correctly
• After applying the aforementioned workaround, in Import change character range 0 from '0'-'9' to '0'-'5'. Missing glyphs are displayed as blocks with hex values (as expected)
• Again, change the range back to '0'-'9'
  Expected: The text looks correct again
  Actual: No change.
  Workaround: You need to reopen the scene or reassing the png to LabelSettings for the changes to display correctly

This are just to examples, which work as expected in 4.2.1-stable. Here's a video showing the issue were for some reason it fails the first to update the first time but works when changing the value back.
https://github.com/godotengine/godot/assets/526829/528b99cb-0df9-4ac1-b4a2-8eec19401c3c

I assume it's related to emit_changed() not being called under some circumstances

Minimal reproduction project (MRP)

fontdata-mrp.zip