Shortcode expansion inside attributes requires single quotes

Bug description

Hello,

I have a Quarto project with a document and an associated variables file (_variables.yml). When I try to use one of these shortcodes in the fig-scap option, it is not replaced by its associated value. Additionally, and depending on the quotes used for the content of the fig-scap option, the results are different:

• If single quotes are used, the shortcode is expressed in its original form (e.g. {{< var vars.ttx >}}).

• If double quotes are used, the reference to the figure and its caption is completely broken and so it is not appearing in the list of figures.

Steps to reproduce

I created a github repository with the minimal reproducible example:

https://github.com/marianoibaldi/figscap.git

Expected behavior

The text displayed in the list of figures should appear as: Short text TLex

Actual behavior

Unwanted behavior is highlighted in red in the figure.

Your environment

• IDE:RStudio 2024.09.1+394
• OS: Windows 10 Pro 22H2

Quarto check output

quarto check
Quarto 1.6.39
[>] Checking environment information...
Quarto cache location: C:\Users\User\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
Pandoc version 3.4.0: OK
Dart Sass version 1.70.0: OK
Deno version 1.46.3: OK
Typst version 0.11.0: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
Version: 1.6.39
Path: C:\Users\User\AppData\Local\Programs\Quarto\bin
CodePage: 1252

[>] Checking tools....................OK
TinyTeX: (external install)
Chromium: (not installed)

[>] Checking LaTeX....................OK
Using: TinyTex
Path: C:\Users\User\AppData\Roaming\TinyTeX\bin\windows
Version: 2024

[>] Checking basic markdown render....OK

[>] Checking Python 3 installation....(None)

  Unable to locate an installed version of Python 3.
  Install Python 3 from https://www.python.org/downloads/

[>] Checking R installation...........OK
Version: 4.4.2
Path: C:/PROGRA1/R/R-441.2
LibPaths:
- C:/Users/User/AppData/Local/R/win-library/4.4
- C:/Program Files/R/R-4.4.2/library
knitr: 1.49
rmarkdown: 2.29

[>] Checking Knitr engine render......OK