Hmm, on my 1000 I open the list of courses, browse to the one I want and click “ride”. If I’m at the start I’ll be offered to “start riding immediately” and if not “would you like to navigate to the start?”. Either way, I’ll normally say “no”. When I’m ready to go, I just hit the (physical) start button and it will start the ride and commence the course following. If off-course, it will notify me, but otherwise it will just track the course as you’d expect. I have never used navigate to start of ride (which enables the turn-by-turn nav), and I would suspect that this is probably why yours doesn’t work.
Every now and then, it does screw-up mid-ride (always after an extended stop with the Garmin turned off) and I’ll need to go back into courses, re-select it and it picks up where it left off. The activity in progress is unaffected.
I create them on Garmin Connect
Being honest, both Garmin and Strava’s course creation tools suck and I think that very few people here use them. Personally, I use BikeHike and save my courses as “GPX Track” (which includes elevation data). I then either manually copy the GPX file to the Garmin via USB or, more recently, use the gimporter app and its matching Android app.