Description:
When opening the "master slides" tab in the sidebar, only my user templates have a preview. The system-installed ones don't show a preview, rendering  the whole idea absurd. After right clicking on any of the templates, all previews are shown.

Steps to Reproduce:
1.Open Impress with any slideshow
2.Open the sidebar and navigate to the "master slides" tab
3.

Actual Results:
Only some previews are shown (user-created ones). After right-clicking on any of the templates (both with or without preview), previews are shown.

Expected Results:
Previews should be shown immediately.


Reproducible: Always


User Profile Reset: No

Additional Info:
[Information automatically included from LibreOffice]
Locale: en-US
Module: PresentationDocument
Version: 24.8.1.2 (X86_64) / LibreOffice Community
Build ID: 480(Build:2)
CPU threads: 6; OS: Linux 6.8; UI render: default; VCL: kf5 (cairo+wayland)
Locale: en-US (en_US.UTF-8); UI: en-US
Ubuntu package version: 4:24.8.1-0ubuntu0.22.04.1~lo1
Calc: threaded
[Information guessed from browser]
Operating System: KDE neon 6.0
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.6.0
Qt Version: 6.7.2
Kernel Version: 6.8.0-45-generic (64-bit)
Graphics Platform: Wayland
Processors: 6 × AMD Ryzen 5 4500U with Radeon Graphics
Memory: 15,0 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: Acer
Product Name: Aspire A515-44G
System Version: V1.12