To set up Forge Gradle, run gradlew setupDecompWorkspace. To generate an IDE project, run gradlew eclipse (for Eclipse) or gradlew idea (for IntelliJ IDEA). To run in a release environment, you'll ...

(I wish I could specify a concrete other mod as cause of the problem, but I'm honestly convinced it is that broad an issue.) After adding mod after mod to my custom modpack during the last few months, ...