Unexplainable Gradle issues

[tonvanbart]

I just updated my fork of this project from origin/master, cloned it on a new machine, and started working on master in IntelliJ.
After adding the spring-kafka dependency and hitting "refresh" in the Gradle pane, I get the following error message in the build pane:

Gradle could not start your build.
> Cannot create service of type BuildTreeActionExecutor using method LauncherServices$ToolingBuildTreeScopeServices.createActionExecutor() as there is a problem with parameter #1 of type List<BuildActionRunner>.
   > Could not create service of type FileAccessTimeJournal using GradleUserHomeScopeServices.createFileAccessTimeJournal().
      > Timeout waiting to lock journal cache (/Users/ton/.gradle/caches/journal-1). It is currently in use by another Gradle instance.
        Owner PID: 10624
        Our PID: 10700
        Owner Operation: 
        Our operation: 
        Lock file: /Users/ton/.gradle/caches/journal-1/journal-1.lock

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

Note: I'm not a Gradle user (guess why), I'm assuming the mentioned lock file just got created. As an experiment I quit IDEA, deleted the whole /Users/ton/.gradle directory, and tried again but with the same result.
Any tips on how to get this project working? I'm on OSX Monterey (12.4), Java 11 (GraalVM), IntelliJ 2021.2.1 Ultimate. Thanks!