I run Tomcat from IDEA run config, using an artifact configured within IDEA. I have breakpoints set. When running in debug mode, it never stops at the breakpoints. Standard processes started from main method do stop at breakpoints. I don't have breakpoints muted.
I saw this with 2020 and 2018 versions of Intellij.
This used to work for years with the same code, same run config back when I was running Intellij 2018 or earlier and Tomcat 8.0. However, I can't run that combination anymore to prove it still works because I get some new error regarding loading a jar file and annotations.