I have submitted an official support ticket for this, but wanted to post here in case anyone else has noticed this behavior as well.
In Octane 2025.5 Blender (custom build 30.11) - Octane Area Lights worked as expected between light power/size relationship. However, Octane Area Lights in 2026.5 (Addon build 31.12) there seems to be a bug, you do not get the desired/same result using the same metrics. HOWEVER, it seems to be specifically the Octane Area Light itself, if you build the same light/same node setup, using a Mesh Plane, you will get the same result as in 30.11. Scale, size, everything else is exactly the same.
See screenshots for comparison.
Windows 10, RTX 5090
Octane Area Lights are broken in 31.12
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Before posting a bug report, please check the following:
1. That the issue has not already been disclosed
2. That the issue is specific to this plugin, and not Octane in general (Try reproducing it in Standalone)
Bugs related to the Octane Engine itself should be posted into the Standalone Support sub-forum.
All bug reports should include the information below, along with a detailed description of the issue and steps to reproduce it.
A. Operating System, including version (i.e. Win 7, OSX 10.11.2, Ubuntu 14.04, etc.)
B. Graphics Card(s) model (i.e. GTX 580 - 3GB, TITAN, etc.)
C. RAM Capacity (i.e. 6 GB)
D. Nvidia driver version (i.e. 7.50, 7.5.22)
E. OctaneRender Standalone version, if installed (i.e. 2.24.2, 2.23, etc.)
F. OctaneRender plugin version (i.e. v2.25 - 2.21)
G. Host application version, including build number if available (i.e. 3ds Max 2016 Build 18.0)
Before posting a bug report, please check the following:
1. That the issue has not already been disclosed
2. That the issue is specific to this plugin, and not Octane in general (Try reproducing it in Standalone)
Bugs related to the Octane Engine itself should be posted into the Standalone Support sub-forum.
All bug reports should include the information below, along with a detailed description of the issue and steps to reproduce it.
A. Operating System, including version (i.e. Win 7, OSX 10.11.2, Ubuntu 14.04, etc.)
B. Graphics Card(s) model (i.e. GTX 580 - 3GB, TITAN, etc.)
C. RAM Capacity (i.e. 6 GB)
D. Nvidia driver version (i.e. 7.50, 7.5.22)
E. OctaneRender Standalone version, if installed (i.e. 2.24.2, 2.23, etc.)
F. OctaneRender plugin version (i.e. v2.25 - 2.21)
G. Host application version, including build number if available (i.e. 3ds Max 2016 Build 18.0)
