Math block in markdown doesn't get syntax highlighted if it is indented and preceded by non-indented text

[kzvi]

Issue Type: Bug

In this markdown file:

a
    $$
    \frac{1}{2}
    $$

The math block doesn't get syntax highlighted.

VS Code version: Code - Insiders 1.62.0-insider (Universal) (34eeebd, 2021-10-15T05:15:40.239Z)
OS version: Darwin x64 20.6.0
Restricted Mode: No

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-9600K CPU @ 3.70GHz (6 x 3700)
GPU Status	2d_canvas: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: enabled opengl: enabled_on rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled webgl: enabled webgl2: enabled
Load (avg)	3, 2, 2
Memory (System)	16.00GB (1.55GB free)
Process Argv
Screen Reader	no
VM	0%

Extensions: none

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