When picking "Tools", "Burn Disk", "Blu-ray Disk", the only option I can pick is "Render image only". I cannot pick "Render image and burn" or "Burn existing image file". After updating to Vegas 15 Edit, I was able to burn one Blu-ray disc but after editing the video, I cannot burn another one! I am using Windows 7 Pro.
What are you using to burn? Is the drive showing in Windows Explorer.
I ask because a Windows Update, possibly months ago, stuffed up my external Blu-ray burner until I reinstated the correct driver.
My Blu-ray drive is OK because it shows in Windows Explorer and I can burn a DVD using it and did burn one Blu-ray on it as mentioned. I Have not updated drivers.
While waiting for someone to come up with a solution (Have you tried toggling "Skip drive database... in Options/Preferences/CD Settings), you could try using the .iso file to burn with alternative software such as ImgBurn.
Is there also Use Legacy Disk Drivers you could toggle with in the CD settings?
I tried toggling "Skip drive database... in Options/Preferences/CD Settings and it made no difference.