Prerequisite: Unity Accelerator must be installed on the system

Reproduction steps:
1. Download the attached "ShaderCmpTests.zip" project and "repeatBuild.bat" script
2. Replace the command line arguments in "repeatBuild.bat" to point to your Unity installation and project path
3. Run the "repeatBuild.bat" script
-- Observe the freeze

Reproducible with: 2020.1.0a22, 2020.1.17f1, 2020.2.0f1, 2021.1.0a10
Not reproducible with: 2019.4.16f1, 2020.1.0a21
Could not test with 2018.4 (Accelerator requires 2019.3 or newer Editor version)

Notes:
- not reproducible without Accelerator connected
- sometimes also freeze on "Mesh data optimization - Resolving used channels"
- reproduced using NVidia GeForce GTX 960, AMD FX(TM)-8350 Eight-Core Processor 4.00 GHz, Windows 10

repeatBuild.bat script:
#127.0.0.1:10080
#http://127.0.0.1/dashboard
ECHO OFF
for /l %%x in (1, 1, 100) do (
ECHO Begin build at %time%
"C:\Program Files\Unity\Hub\Editor\2020.1.15f1\Editor\Unity.exe" -quit -buildTarget Standalone -projectPath "C:\ShaderCmpTests_20.15" -executeMethod Builder.BuildPlayerActiveTarget -EnableCacheServer -cacheServerEnableUpload false -cacheServerEndpoint 127.0.0.1:10080
ECHO Completed build at %time%
)
ECHO Completed
PAUSE