You are very welcome, I am glad I could offer some help, hopefully you will be back to getting some more luxuriant sized harvests soon.
I did a bit of searching and there isn't a lot of information about this topic out there, but there is some supported science behind various flame types emitting visible light as well as IR and I found a few interesting articles and the data suggests that the blue flame light that your gas heater is emitting is a blend of violet, blue, and green light, or it is within these spectrum ranges that this light is being made visible, and since blue light is more ideal for vegative growth, I believe that this light coming out from the new heater you're using is confusing your plants by giving them mixed signals between the types of light that they are receiving.
Also blue light is emitted at a higher frequency than other colors of the spectrum besides purple/violet, so the light has more ability to permeate the atmosphere and organisms than other types of light, basically blue light has more energy behind it than other types of light, for instance red and yellow are emitted at a lower frequency, so basically the blue light itself could be more harmful to flowering plants than if the light were a color that was lower on the light spectrum scale.
Here is a link that I think might be helpful, it's not exact but it does show that there is some science behind the issue that you are dealing with:
http://scienceline.ucsb.edu/getkey.php?key=5621
Myself I'm fascinated by light sources and all the various spectrum properties that each type of light brings forth, so I too found this information valuable to learn and I do look forward to an update to see if this had as much effect on the growth of your flowering plants as we have theorized, and hopefully others can learn from this information that you have helped us to stumble across as well, it's something we may not have learned otherwise, so at least speaking for myself I thank you as well and I do hope that you will be able to put this case to rest soon.
Happy growing and may these low frequency positive vibes im sending your way find you, take care friend.