Instead of direct to, you can add the IAF to your flight plan. Any app is going to seem like it has problems until you learn all the nuances. That's not to say it's perfect, but it's the best I've used and I've used them all except ForeFlight. Also, the waypoints are there if you overlay the appropriate approach plate. Also, they just added all of those waypoints to the beta version. Don't believe everything you read.
On the other hand, some would say your old flight plan should go away once you are flying an approach. You obviously know what airport you are going to and you have the geo-referenced approach in front of you. Why would you want or need your previous flight plan unless you were making an approach at one airport and then heading to another airport?