Plug ins not working

Audacity 2.3.2 / Mojave 10.14.5

Help please! I use the W1 limiter plug in and have a new MacBook Air. I’ve installed Audacity and the plug in, enabled it in the effects tab however it doesn’t load properly. I’ve tried a few things but no joy. See image.

Any suggestions would be much welcomed! I have also tried another similar plug in and the same thing happens.