I used the /j and the /d, but if I remember correctly, the /d cannot span drives, or even partitions on the same drive, whereas /j can (or something like that). Whatever, I tried every combination conceivable. Using LSE takes the guesswork out, as it will create the appropriate link itself, all you have to do is select a folder (or file) and a link destination in explorer. It's all mouse right click context menu based.
I'm now convinced the problem is down to the ramdrive being seen as removable media. What I need is a way to make it "fixed". There must be an answer, as you can make a thumbdrive fixed.
I'm going to contact Dataram directly to see if they have a solution, as I can't believe I'm the first person who has come across this issue. When I get some sort of answer I'll post it here so it might help someone else in the future.