After I upgraded to IntelliJ 2021.1, test classes are not auto-compiling

I had to explicitly run "mvn compiler:testCompile" for updating any changes to the test class

Hello,

Could you please attach screenshot from "Settings/Preferences | Build... | Compiler". Also please attach screenshot with your Run Configuration.

Here are the 2 screenshots.

Am I got you right that if you change test class and run "PlatformApps..." configuration then test classes aren't build and old code is used?

That's right, Junit test classes are not auto-compiling to pick the new changes, thus it's using the old code.

Is it reproducible with some sample project example?