ITunes Smart Playlists: Songs not played in the last 6 hours

There are a couple of potential solutions to this problem. I say potential because everyone's listening habits and needs are different, so your mileage may vary. Here goes:

The Smart Playlist problem is not new, and certainly not unique in your case. There seems to be an overall problem with Smart Playlist syncing through iTunes Match (1) across different devices, (2) with any expediency (usually takes >= 48 hours), and (3) with respect to honoring certain rules (e.g., number of songs allowed). Another common theme seems to be that "nested" playlists cause even more of a problem than standard Smart Playlists. Nested lists are those that are created when you use your option key to turn the + into an ellipsis (...), which creates a sub-rule for your master rule.

Solution 1: Dumb it down

Create a standard playlist (Dumb) and give it the same name as your Smart playlist. Copy the content from Smart to Dumb. Sync your device, computer, whatever. Rinse, wash, repeat for each Smart Playlist you want to have properly represented on your other devices. This works.

Solution 2: Really Dumb it Down

Do your best to avoid the aforementioned nested playlists. This may require you to build several smaller smart playlists with limited criteria. Not the easiest workaround, but we're going for functionality here, right?

Solution 3: Really make your "Recently Added" folder songs that are "Recently Added"

For your "Recently Added" folder, tack on just one more rule to force songs added after a date, rather than only within the last two weeks (see pic below)

So, I hope this gets you at least a little closer to your goal. I tried to add as much info as I could here since, one more time: everyone's listening and categorizing habits are different :-)
You may find other variations on these, but do realize that, at least for now, this is a server-side problem and workarounds like these represent the best available solutions.

In the smart playlist edit panel, just specify a max limit for the number of songs (eg: max 1,000 songs or max 4GB), and also choose that it should choose the highest rated songs to reach that limit.