Sorry I wish I had joined the conversation sooner
Here is what I have played with...and gotten results!
I have had my VFT's flower ( which they are again right now!) my pings flower and the Sundews are always trying to.
All the plants that I have are grown under artificial lighting. No CP's are grown outdoors ( until the Spring when I get the greenhouse)...anyway.
The cool white tubes DO NOT put out the right spectrum for the plant to flower.
I have found the warm lights ( the red bulbs ) puts out the right color to get the flower to open. So I have mixed cool, warm, and plant lights in my lab. With that mix...I get flowers all the time. Before that ...I was having the same problem...I would get the flower spike but the flower wouldn't open.
The only other way to have them open is to put them outdoors where they will get the full spectrum of light needed to flower.