You should be able to start a new thread from one of the main category pages (not within an existing thread or topic). There’s a blue oval in the bottom right corner, hover your cursor over it and it should turn round—click on it to start a new thread.
Search your Documents folder for the bbworkspace folder; the path to your projects should be bbworkspace/user_lib/projects/ If you don’t have a bbworkspace folder, then you need to create one and move user_lib and default_lib to that folder. If you’re not using the notarized version of the BBM for macOS, you’ll need to download and install it. If this is the case, you might be better off Exporting your current project from the BBM to your SD card and then deleting the BBM from your computer as well as any BBM files and folders from your computer.
This is a known issue and you will have to use BeatBuddy Manager (BBM) File - Export - Project to SD card.
Do any of your folders or song names use a period or any non-supported character? If so, that might be the problem but it’s hard to say given the amount of detail you have provided so far.
If you have not read the user manual for the BBM or the Quickstart Guide, you might find them helpful: * Link (in blue font) to new user resources
If you need some more help, feel free to reach out to Support at Support, support@singularsound.com