See screenshot for the assert, which happens when saving the project.
It seems like it only happens for this file
submodules/JUCE/modules/juce_audio_plugin_client/VST3/juce_VST3ManifestHelper.mm. Same assert on both windows and mac.
I don’t have the assert if I use an absolute path, e.g.,
C:\Users\UserName\JUCE\modules, or the global JUCE module path.
This is with the AudioPluginDemo straight from the tip of develop (