I am having the same problem also, and I only paid for Nebulocity in August so well chuffed.
You seem to be a bit more familiar with computers than me. Would it be possible for step by step instructions as to how you action the workaround above?
I'll do my best , I'm no programmer.
If you are running MacOS Catalina make sure you have the Pre-release Beta release of Nebulosity 4 -64 installed the earlier ones are 32 bit and won't work anymore on Catalina.
If you double click on the Nebulosity4-64_resign.dmg file you downloaded and go to the image on the desktop and open it,
Then right click on the Nebulosity4-64.app inside and select show package contents.
Under contents you will find Resources and the file you want is libusb-1.0.0.dylib Right click and copy then paste it to say the desktop .
You need to copy the file to /usr/local/lib/
Easiest way is to use a file utility I use Forklift but you can use finder but you need to access the hidden files.
If you are comfortable with Terminal you can use that.
From the prompt $
cp /usr/local/lib/libusb-1.0.0.dylib /usr/local/lib/old-libusb-1.0.0.dylib
This keeps a backup of the original
Then you need to copy the file from the desktop
cp /Users/cliffs/Desktop/libusb-1.0.0.dylib /usr/local/lib
'cliffs' needs to be replaced with your User Account Name.
Sounds difficult but actually easier to do then explain. Maybe I should have pictures or video ?
Hope that helps if you attempt it, hopefully this will be fixed once Nebulosity 4-64 goes to stable version.
I did tell Craig Stark if he reads my email.