IDEA is showing a new error with 1.3.60 on all my unit test method names: "Name contains illegal chars that can't appear in JavaScript identifier"

Thanks, filed https://youtrack.jetbrains.com/issue/KT-35031 MPP, IDE: JS-specific frontend error with no JS target (NAME_CONTAINS_ILLEGAL_CHARS)

Is it only an IDE issue, or do you get an error running tests from gradle CLI as well?

IDE only. Everything fine when running tests

it just causes those frustrating red lines that we OCD developers can't stand to see in our source code/project tree

As a developer with OCD myself, I completely understand that. We’re working on fix and hope to deliver it ASAP 🙂