Got it working! But it seems like a workaround.
First, I enabled jxBrowser debugging via the JVM arguments
-Dignition.client.jxBrowser.logLevel=DEBUG
That gave me the following error in the log
23:28:12.383 DEBUG [Chromium] [51508:23944:0417/162812.383:ERROR:chrome\browser\chrome_browser_main_win.cc:1025] Since version 138, Chromium launched with admin privileges will automatically remove the admin permissions and restart. The library does not support Chromium restarts. If you need to keep the admin permissions, use the `--do-not-de-elevate` switch.
23:28:12.418 DEBUG Chromium process exit code: 0
My installation is not set to run as admin, so I added the flag it says in the error to the same JVM arguments in the launcher
-Dignition.chromium.switch.do-not-de-elevate
And success! The designer is showing the perspective module now