Are you sure you are using the right version of the plug-in?
It is displayed in the menu and the panels.
Regarding your problem of rendering stuck at 99%, reproduces it
- without the enhencement of the external brightness?
- with a width of 640 pixels for example?
- with the standard photo panel of Sweet Home 3D?
It may happen that the rendering engine "crashes" on a particular object that requires a lot of computation.
The estimated remaining time is based on the percentage of progression and the elapsed time.
Enko Nyito