At times it may take a very long time for your project to import into the Snyk User Interface. We have seen these cases with Yarn workspaces. You can check if its a Yarn Workspace project by inspecting your package.json and finding the keyword workspaces
Reason: This is case specific and we build the tree by talking to the vulnerabilties which is an extremely slow process
Workaround: As a workaround you can use the Snyk API (here) and send yarn.lock with every package.json file