For the longest time my ignored tags have been working but today they are not.
They work on the home page but not the /questions page. However, if you choose the "Gray out questions" option then that fails.
Arqade is the only site I've ever had a long-standing ignore list so I don't think I can blame cache.
The same behavior seems to be exhibited on Stack Overflow but I added those ignore tags just moment ago so cache could be an issue.
If it matters, I am using Chrome x64 v91.0.4472.77 on Windows 10
Via comments, this issue has been confirmed for Watched Tags as well.