This issue usually occurs when you're running Tabnine on a machine without a GUI. The following options may help:
Use port forwarding to view the config panel from your local machine. If your remote machine's address is firstname.lastname@example.org, and Tabnine is listening on port 1123, the following command will do this:
ssh -L 1123:127.0.0.1:1123 email@example.com
You can then access the config panel by copying the URL printed by Tabnine into your local web browser. Note that the string of random characters must be included, otherwise the config panel will hang with a "Lost connection. Please reopen the Tabnine Hub" message.
Use a web browser that doesn't require a window manager to access the config panel from the remote machine.
Copy a working config file from another machine. You can find the file location by typing:
to the end of the path.