Reproduction steps:
1. Download and extract user's project "AssemblyUpdaterSaturation.zip"
2. Open Assets folder inside Project folder in File Explorer
3. Delete all files with the ".meta" extension (you can sort by type to make it easier)
4. Open the project
5. When API Update Required pop up appears, click on the "I Made a Backup. Go Ahead!" button
6. Wait for the project to open

Expected result: Project opens, assemblies are compiled successfully and no errors are thrown
Actual result: Project opens, assemblies are not compiled successfully, and "NotSupportedException: The number of WaitHandles must be less than or equal to 64." error is thrown

Reproducible with: 2019.1.0a12, 2019.4.19f1, 2020.1.17f1, 2020.2.3f1, 2021.1.0b5, 2021.2.0a3
Not reproducible with: 2018.4.31f1, 2019.1.0a11

Note1: The API Update Required window doesn't pop up in 2021.2.0a3, but the error is still thrown
Note2: Even if you press the "No Thanks" button in API Update Required window, the error is still thrown