Mermaid preview fails

Type: Bug

Code a mermaid diagram within a markdown file. The diagram is not rendered in preview.

VS Code version: Code 1.131.0 (e4c7e7b1d6d060162f4aa7f8225271b67ce1df75, 2026-07-28T10:51:25Z)
OS version: Windows_NT x64 10.0.26200
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) Ultra 7 268V (8 x 3302)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x8086, DEVICE=0x64a0 [Intel(R) Arc(TM) 140V GPU (16GB)], DRIVER_VENDOR=Intel, DRIVER_VERSION=32.0.101.8508 *ACTIVE*
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8875
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|undefined|
|Memory (System)|31.57GB (11.93GB free)|
|Process Argv|--crash-reporter-id a7ce1cd3-37c8-43c2-8005-abdd849f4e5d|
|Screen Reader|no|
|VM|0%|
Extensions (34)

Name|Identifier|Author|Version
---|---|---|---
Rexx Language Support|broadcommfd.lsp-for-rexx|BroadcomMFD|0.0.24
Terminals Manager|fabiospampinato.vscode-terminals|fabiospampinato|2.1.2
Insert GUID|heaths.vscode-guid|heaths|1.9.0
Bob Shell Companion|ibm.bob-shell-vscode-ide-companion|IBM|1.0.4
QubitSense - Quantum Development Assistant|lielisk.qubitsense|Lielisk|0.0.46
Rainbow CSV|mechatroner.rainbow-csv|mechatroner|3.24.1
Azure Functions|ms-azuretools.vscode-azurefunctions|ms-azuretools|1.22.0
Azure Resources|ms-azuretools.vscode-azureresourcegroups|ms-azuretools|0.12.7
Container Tools|ms-azuretools.vscode-containers|ms-azuretools|2.4.5
C# Dev Kit|ms-dotnettools.csdevkit|ms-dotnettools|3.20.199
C#|ms-dotnettools.csharp|ms-dotnettools|2.140.9
.NET Install Tool|ms-dotnettools.vscode-dotnet-runtime|ms-dotnettools|3.1.0
Python Debugger|ms-python.debugpy|ms-python|2026.6.0
Pylint|ms-python.pylint|ms-python|2026.6.0
Python|ms-python.python|ms-python|2026.4.0
Pylance|ms-python.vscode-pylance|ms-python|2026.3.1
Python Environments|ms-python.vscode-python-envs|ms-python|1.36.0
Jupyter|ms-toolsai.jupyter|ms-toolsai|2025.9.1
Jupyter Keymap|ms-toolsai.jupyter-keymap|ms-toolsai|1.1.2
Jupyter Notebook Renderers|ms-toolsai.jupyter-renderers|ms-toolsai|1.3.0
Jupyter Cell Tags|ms-toolsai.vscode-jupyter-cell-tags|ms-toolsai|0.1.9
Jupyter Slide Show|ms-toolsai.vscode-jupyter-slideshow|ms-toolsai|0.1.6
Dev Containers|ms-vscode-remote.remote-containers|ms-vscode-remote|0.466.0
Remote - SSH|ms-vscode-remote.remote-ssh|ms-vscode-remote|0.124.0
Remote - SSH: Editing Configuration Files|ms-vscode-remote.remote-ssh-edit|ms-vscode-remote|0.87.0
WSL|ms-vscode-remote.remote-wsl|ms-vscode-remote|0.104.3
Remote Development|ms-vscode-remote.vscode-remote-extensionpack|ms-vscode-remote|0.26.0
Hex Editor|ms-vscode.hexeditor|ms-vscode|1.11.1
PowerShell|ms-vscode.powershell|ms-vscode|2025.4.0
Remote Explorer|ms-vscode.remote-explorer|ms-vscode|0.5.0
Remote - Tunnels|ms-vscode.remote-server|ms-vscode|1.5.3
qiskit-linter|qiskit-support-extensions.qiskit-linter|qiskit-support-extensions|0.1.18
XML|redhat.vscode-xml|redhat|0.29.3
YAML|redhat.vscode-yaml|redhat|1.24.0

A/B Experiments

```
vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31463988
aj953862:31281341
4f60g487:31327383
envsactivate1:31551504
478i5457:31544283
cloudbuttont:31379625
42190218_ostrepl:31403339
bj468946:31457056
ddidtcf:31399634
ec5jj548:31422691
cp_cls_t_966_ss:31526232
4je02754:31466945
c3h7c220:31478652
ge8j1254_inline_auto_hint_haiku:31490510
cp_cls_c_1081:31454833
conptydll_true:31498968
e9c30283:31461165
test_treatment2:31471001
c9b86496:31447327
control_6dc23131:31555649
idci7584:31464702
e3e4d672:31494082
ei9d7968:31496641
nes-extended-on:31455476
chat:31457767
8hig5102:31480529
89g7j272:31518289
7e187181:31503455
i2gc6536:31499202
52612955:31516516
ghj88844:31499326
ddid_c:31478207
hmra_i5g22:31518061
7df3h592:31512476
cp_cls_t_1082:31535311
logging_enabled_new:31498466
db5d2638:31499441
jb_cp_cls_t_632:31543129
56dj4588:31512888
32d76977:31512328
ha629193:31508444
cdk-lw-on:31524445
f9bf7985:31543584
jh5f2457_c:31540921
hgf2d445:31529595
8hfba999:31537718
jbcp_cls_pctr_t:31531130
61138546:31518536
cp_intellij_t_nes:31548657
jf4hg949:31526829
nes-curr-leftover-1500:31538366
ahp-both-windows:31556933
h561g132:31533256
sessions_3:31532893
ihg5j128:31534457
f412h606:31551416
7g2b5551:31542111
max-result-200:31551155
5fe6f778:31554331
allow-none:31555437
6i51c363:31551401
c7c27ce7:31554789
8hc4g144:31558143
1532g621_copy:31554320
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
a1hcc538:31559322
session-mark-done:31558131

```