I have the exact same problem. I add new music to my library every few days and my iPod syncs the smart playlists just fine. My iPhones and iPads will not live update on the device.
I also use date added <30 days. When I create a new SPL the first sync works fine and maybe once a month it will live update and sync the changes to the device but normally I just delete & recreate the playlist after a dozen failed attempts and that works, it's just a pain because I'll have to reselect that playlist on every iPhone and iPad.
What's odd is, after more than a year of having this problem, I can confirm the following:
1) the new music is copied to the device even though it doesn't show up on the playlist on my devices
2) it works fine on my classic iPod, shuffle and Nano
3) while still connected to iTunes if I select the smart playlist shows correctly but but looking at the playlist on the device does not show the new music recently added.
4) smart playlist default sorting doesn't work on devices either, but works on my iPods. Example, I have this playlist to sort my date added descending, but on the iPhones the playlist (even on the initial sync which works fine) the list is still sorted from oldest to newest.
With every update I'm hopeful that Apple will address this because I know I'm not the only who has this issue, but apparently we're stuck with my favorite development response which is "well it works on my machine", to which I tell my developers that it's fine if we're going to let the customers use their machine lol.
I'd be willing to prove that this doesn't work with a YouTube video is needed.
Add the criteria "Playlist is Music" to your smart playlist, where "Music" is the general category for music which can be treated as a playlist for SPL criteria. This will break Live Updating on the device, but should populate the playlist on your iPhone. It will update with each sync to iTunes.
As for your sorting issue, did you select "Copy to Play Order" after you sorted the playlist how you wanted? You need to do that to save the order, then sync your device. But, the criteria above may solve the sorting problem too.