After some more searching I found some others who had experienced this error aswell. It’s an ‘unspecified OIIO error’ and is apparently a texture error. The thread suggested deleting all the textures and re exporting them from substance, and also unchecking the ‘auto-convert textures to .TX’ in the render settings, however neither of these approaches solved their problem. I was unable to attempt the re-exporting textures option so I tried the latter, but as expected it didn’t solve the issue.
Another thread was answered by an autodesk technician, who offered solutions such as ‘You’re rendering on OSX, so I don’t think that Windows path is going to work’ & ‘You’re running MtoA 184.108.40.206, not MtoA 220.127.116.11′ but neither of these seem to have solved anyones issue either.
I’ve found an official Autodesk page for the error though that states that the ‘error happens when Arnold cannot access textures for various reasons. Often happens when network rendering and the user account used does not have access to textures stored on network shares.’
Even so, the filepaths should still have worked, so I’m not sure how this might have happened. I’ll look into the file locations of all the textures again to try and be sure.
1st thread source: https://forums.autodesk.com/t5/maya-shading-lighting-and/issue-with-arnold-rendering/td-p/6926189
2nd thread source: https://forums.autodesk.com/t5/maya-shading-lighting-and/error-texturesys-unspecified-oiio-error/td-p/7199906
Autodesk knowledge network page: https://knowledge.autodesk.com/support/maya/troubleshooting/caas/sfdcarticles/sfdcarticles/Maya-Arnold-Texturesys-error.html