Cannot resolve overloaded method, but code compiles and runs

I am getting some red highlighting syntax for my overloaded methods, but the code still compiles and runs. I've attached my example below. Anyone know why this red highlighting is happen / how i can get rid of it? 

using intellij idea ultimate 2020.1, scala 2.12.8 and jvm-1.8

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Found this when I had a similar issue. Posting in case it helps someone else.

I fixed this by changing Erro Highlighting from "Built In" to "Compiler". This setting is under Preferences > Languages & Frameworks > Scala