Hmm, I can't seem to reproduce it so far.
Which GPU are you on? I haven't done much testing outside of Nvidia cards lately.
https://drive.google.com/file/d/16tU_WJbNLCHJ8NiP1uGV3RA-jXnjSULf/view?usp=shari...
If it works for you, you should see a red sphere in the middle with the whole camera having the JPGPU filter.
If it doesn't (like on my PC) it will seemingly freeze after the unity logo.
Another thing to note is that your demo of JPGPU ( https://ompuco.itch.io/hlwl ) works fine when I test it out in my web browser.