This is not Adobe. Rather user to user. If you want to contact Adobe, your likely route is via Adobe Chat.
If you have a feature request or bug report, then consider filing a Adobe Feature Request Bug Report Forum with Adobe
The likelihood of an Adobe engineer seeing your thread here is essentially slim to none.
Your results are very interesting but lots more variables to consider.
Do you have any version of Premiere Elements other than 12? It would be interesting to learn if a prior version's burn
dialog would present with the Media Not Preset issue for your burn to Blu-ray System 1. That is easy enough done with a tryout of
11 or 10 or 9 from the following web site. ProDesignTools: Adobe® Developments in Focus
On the other side of the coin, you could give the new version a look in this regard. A new version is expected at the
end of September 2014.
As an aside, have you updated 12 to 12.1 Update, using an opened project's Help Menu/Update. If not, I would encourage
you to do so. It does correct an Expert workspace text styles issue plus other matters undefined by Adobe.
I am running PE 12.1. I do not have much time to diagnose this by reverting to older versions; as I have already struggled with this for over one year, I will use the work-around I found. My intent was to help Adobe improve their product, and to help others who have similar issues with this bug. It's a shame that Adobe doesn't pay attention to their users; their customer satisfaction will suffer.
As for PE13, I have no plans to upgrade. If Adobe wishes to provide me a free licensed copy to try out, I will gladly accept their offer and report back on my findings. I will await the offer email from Adobe.:-)
The Adobe presence in this forum typically occurs here when a new version is released, the PRE_help directed at the new product, and at other sporadic undefined times.
If you do not attract the attention of PRE_help using your Premiere Elements12/12.1 thread, then, if you purchased from Adobe, you might want to contact Adobe via its Adobe Chat to find out about
If Adobe wishes to provide me a free licensed copy to try out, I will gladly accept their offer and report back on my findings. I will await the offer email from Adobe.:-)
As an aside for informational and non promotional reasons, are you aware that Premiere Elements 13, the new version released September 24, 2014, now offers ISO image in its burn to. Now Blu-ray has ISO image as well as the burn to choice. At this time, I have only the tryout and am working my way through it.
Best wishes for what your decisions are.