P. Maudiae flower not fully open
 

This pic was taken 12/4. As of today 12/19 the flower hasn't opened too much more. What's going on ?

Sometimes that just happens.

Often it is connected to either being underwatered, or the ambient humidity being too low.

While you can't get a good view of the dorsal I think it looks kind of neat.

Bill

I tried the following
 

I think I'm watering it properly, 2x /wk, excellent drainage. The humidity level is rather low, mid 30's. I tried putting it on a tray of peebles with water and placed a few containers of water around it. Doing so raises the humidity another 10%. Do you think it's too late? i.e. Will the flower open up any more or this the maximum it will open ?

I think that 2 times a week is not enough for a Paph, especially with low humidity. They don't want to dry out. Try watering it more frequently. (What is appropriate for a Phal, which is an epiphyte, is too little for a Paph which is more terrestrial) Then just sit back and watch... the flower still looks healthy, Paphs can take a looong time to open fully.

good point
 

I'll try watering it more, and see what happens. perhaps 1 additional watering per wk ?

You really can't water by the calendar... you will have to observe how fast it dries out. Give it a good bath (like under the faucet). Lift the pot and feel the weight (or if you want to be more systematic and have a kitchen scale, weigh it) Then check the weight over the next few days. You'll get a sense of how fast it is drying, water accordingly. Just keep in mind the goal... you need to keep it on the damp side. That depends not only on watering frequency but also medium - how big? How moisture-retentive?