Look at your nodes, do you see the L8 in the bottom right? That means the node dropped to 8bits which means it has a limited color range, which in turns causes banding. Select that node and in it's "Base Parameters" set its "Output Format" to forced to 16 bit.
@capone when you select you substance in the explorer window is the Output Size type set to 'Relative to parent' or 'Absolute'? the parent size thing is only usable on relative to parent. But you're probably better off having it set to absolute and then setting the 'Output size' to be higher, try setting it to 1k and see…
3rd attempt. Few issues, firstly the output size at the top (as seen in SD6+) seems to be locked! Can't change it and it's set to 256 even though I originally set it to 512 absolute when starting. So that's why this looks low res. Any ideas how to unlock it? Can't find any answer via google. Secondly I'm getting banding…