recently, windows rolled out an update that affected how webmidi works, but no worries!
you can install the dedicated asio drivers for teenage engineering products, available here: https://teenage.engineering/downloads/usb-asio
also, you should use a browser like brave, chrome, or edge and disable windows runtime midi in the
settings.
to do so, type chrome://flags in your address bar >search for midi >set windows runtime midi to disabled> restart the browser.