Roissy Bus Down today

I just looked and I can see a bus is leaving this afternoon around 3 which is the time I entered

When I tried your itinerary it does show me options Make sure you adjust the time to a normal time during the Paris day. It doesn’t automatically do that time conversion when you go on their website.

Thanks for checking. The Roissy bus doesn't go to La Défense. It stops at the opera. My problem is that the app doesn't show the bus as an option at all..it wants me to take the RER B.

The website shows it. Try there.

Did you select bus as your preferred mode of transportation? The app is going to show you the routes that make the most sense and it will not usually offer the Roissy bus for the trip that you want to make because the RATP app is guided by efficiency. You need to do a Opera to CDG trip and select Bus as your preference and do a separate La Defense to Opera trip to get to Opera. Then just combine them in your head. Or if you want to do the entire thing by bus, select Bus in the spot where it says Preferred Modes of Transportation and use La Defense as your beginning spot and CDG as your destination. In any event if you are willing to take the RER from La Defense, it is super easy -- RER A to Auber and then walk over to the Roissy bus stop. This will not be a free transfer. You can also map the whole thing out on CityMapper, which will offer you the Roissy Bus option if you select the Wheelchair Accessible route.

It would make a lot more sense to take the RER A to Châtelet and change to the RER B for CDG. Cost of the MTA ticket is 11.80€

But if you happen to have spent the night near La Défense. And you also have a Roissy bus ticket in your pocket from a couple of years. Then it may make sense.
Also the bus ride is more pleasant than the RER.

Because we often stay near the Opera Garnier, we like the Roissy Bus, when the schedule is convenient. It's worth something to have less baggage handling.