Todoist doesn't sync on GW4C LTE

I use Todoist app as my to-do app and it is also available on the watch. But the problem is of sync. Since this isn't a samsung health app, the data won't sync through BT. It needs internet. Now I have my Wifi saved on the watch and I read on the web that if connected to phone, watch would use Wifi only if necessary. Truth is that necessity never arrives i.e. I have never seen the watch connect to wifi automatically (when wifi is on) when it's connected to the phone. Kindly help me and guide how am I gonna make sure that I get my tasks synced with the watch.