Hi, thanks for the input everyone.
I’ve tried turning off the filtering and it hasn’t helped, unfortunately.
The color channels already extend to the edge of the antialiasing on the alpha channel, so it ought to work fine as is, but I did try further extending the color beyond the edge of the alpha channel and while it did get rid of the black line, this isn’t really a viable workaround. The textures I’m using are numerous, complex and animated, and having to manually go in and paint around the edges of each texture would take far too long, as well as probably introducing artefacts where the border of the texture is not a single colour.
It seems to me that this is an issue with Maya and not my textures; can anybody think of a cause for this problem? Thanks!