Strange darkening of shader with random node group, can anyone help?

Hi All,
I’ve been using this shader setup for a while, but is now showing darker when applied to other objects.
(scene file link included)
Basically I use it to randomise the position of grain of a wood texture map.
At one point , I thought it was something to do with the rotation of uv island, as it seemed to show darker results for the shader as I rotated an uv island in the uv editor window. ( see render)
This seemed to of stopped now after collection the maps for export, but the same shader is still darker when used on other object collections ( planter walls).
As for the Node group setup, think I found the setup in a video tutorial maybe and to be honest I’m not skilled enough to know how it works.
Any help in resolving in what is causing this would be great

Could you please strip down the Blend file to just the planter and nodes…as it is just too large to just take a look, and evaluate!

I’ll send the textures sepa
Just planters2.blend (2.4 MB)

I downloaded the blend file and could not reproduce the error, neither in evee, nor in cycles render preview, nor in the composite render (btw. I reduced the samples to 32 and switched on denoising, saves a lot of time…):

(Blender Version 2.93.5)

wood_base_AmbientOcclusion.tga (4.0 MB)
wood_base_Height.tga (4.0 MB)
wood_base_Metallic.tga (4.0 MB)
wood_base_Roughness sm.tga (314.0 KB)

wood_basesm_Normal.tga (941.9 KB)

And looking at the material setup, I also couldn’t find anything out of the ordinary. Maybe consider installing a fresh version of blender to check whether it works then?

Thanks for all your, I might try and it from scratch with other textures

I actually don’t think there’s anything wrong with the textures; as I said, it works fine on my end…

I had issues, and it went away if I selected the normal map twice.
Thought it was the metallic map returning 1 for some reason, but nope.
I’m outta time, but I can’t think of what’s going on.

I had the same problem, reloading and reseting the normal map to non colour fixed it.

The funny thing is that the problem was there before I properly loaded the normal map (node wrangler viewer pink missing image.)

I think it has something to do with the UV mapping.

If I unplug everything and plug in a tiled image of an arrow into the colour socket I get this:

There are 3 planks that have the UV’s orientated differently (the arrows point in different directions.) This seems to be the root of the problem. Maybe some UV’s are mirrored.

Edit: I edited the last bit.

I noticed the orientation, and it wouldn’t be my choice, but isn’t something that should do something like this. Unless it’s for sale and UVs are required, I’d do it with a simple instanced mesh, using box mapping with random offsets and mirrorings instead.

Hi All,
Sorry for the late response I was at a Christmas party!!
About the UV’s, yes I rotated a couple of UV in 90 deg rotations because I noticed if the UV where rotated this would result I. The lighter and darker effect to overall shader and thought it may help with the discussion.
I also wondered if the mesh rotation had anything to do with it, but resetting the rotation valves to 0 didn’t change anything.

One thing I did notice though, was that thumb nail preview image for the shader had a dark side.
Literally half of the sphere was shaded black.
I wonder if this was reflecting the error.
I’m on my way home and give it another go when I get in

Rebuilt from scatch and all seems good now, although sometimes when I duplicate the plank and position it, it doesn’t always randomise the pattern.