I’ve had similar problems since updating to a certain version of Logic Pro, must’ve been the same as it was about a year or so ago.
I can open projects that contain Retrologue 2 instances fine, but if I then load another project that contains any Retrologue 2 instances Logic will crash instantly. It will also crash if I change any audio preferences, it must be something to do with reloading the audio device. So to switch between projects I have to quit Logic and reload.
Retrologue can also crash Logic just when you’re tweaking about with the parameters, was just experimenting with sweeping the cutoff and it crashed.
I’ve contacted Steinberg about this numerous times and they’ve offered zero support and don’t seem to care. The problem’s been going on for a year and a half now and they’re well aware of it but are doing nothing about it.
If anyone can help that’d be great!