I had the same issue of maps not downloading over wifi, only showing as queued. I was away without access to my PC so I needed to download directly on the watch.
I found the resolution of connecting to wifi and plugging the watch in to start the download - WITH THE WATCH DISCONNECTED FROM MY PHONE. Didn't seem to matter if I turned off the Bluetooth on my phone or disabled the connection on the watch.
Hope this helps in case you need new maps while travelling.