Bug? JUCE Assertion failure in juce_VST3PluginFormat.cpp in AudioPluginHost

Hello all,
when opening a newly created VST3 in AudioPluginHost i get the following error message in the console

JUCE Assertion failure in juce_VST3PluginFormat.cpp:3479

Which in the file itself is commented

// If you hit this, the plugin has requested a restart from a thread other than
// the UI thread. JUCE should be able to cope, but you should consider filing a bug
// report against the plugin.
JUCE_ASSERT_MESSAGE_THREAD

This is happening on my Fedora machine with JUCE 6.1.4 . All my VST3 projects seem to work fine in REAPER.

Any idea why this might be happening, or how i can fix the error?

Thanks!