… and same here. I was convinced that it was possible (thought I’d done it) but couldn’t repeat.
Also thought you should be able to insert waypoints - as MOS95B95 says above, if you select the leg before you ‘add’ the waypoint, it does insert it.
So between the filters and lat-long custom waypoints manually entered, you can pretty well plan a route to anywhere.
… And to prove it does work, here’s my sightseeing diversion over Lake J B Thomas, enroute to Dallas Fort-Worth 
Just like it should look!
It’s unfortuante that there appears to be no way to click on the map to add a custom waypoint as there used to be.
Having to find the lat+long using another program or hope that there’s some point of interest, nav point etc near where you want to go is a pain.
