I’m testing the Plugin Hosting demo within tracktion’s DemoRunner. I noticed that when adding different Apple default AU plugins and clicking on them to open the plugin window, the behaviors are different. For some (e.g., AUSampleDelay) the plugin windows come up just right when clicking the icon. For others (e.g., AUBandpass) the app keeps running the no plugin window get opened. For others (e.g., AUDelay) the app just crashes. Could this be an issue with the mac OS system version that I’m using? I attached the stack track below but couldn’t figure out too much from the error. Thanks so much for the help 
Can I ask if you’ve tried showing these in the normal JUCE Plugin Host example app?
I’m just wondering if it’s something specific to TE, JUCE or the AUs themselves?
Thanks for the reply! Yes I’ve tried to out the JUCE Plugin Host. What’s really strange to me is that the problematic plugins like AUDelay actually do work on both the JUCE plugin host app and my tracktion app, and the effects are properly applied to audio playback.
The only problem seems to be when I want to open the plugin window view via showWindowExplicitly() when I click on the plugins in the track footer component. So I think that would suggest that this is either a Tracktion with the provided PluginWindow related classes, or an AU thing, which I’d be confused about since the same plugins could be opened with no problem on other DAWs like Reaper
Can you try running with ASan enabled and see if you get more info on the cause of the crash?