Yay - I found the solution.
Yep, it was definitely the frame tweening to blame. Once I changed 'Renderworld tween' to 'Renderworld', it worked perfectly well.
I suspect that it was because I wasn't using 'captureworld' in conjuction with renderworld tween, as the docs recommend I do. Could this be the case?
Either way, I now have transparency fixed! :) Thanks for the help of everyone here, it's because of you guys that I'm able to keep going with Blitz.
Yep, it was definitely the frame tweening to blame. Once I changed 'Renderworld tween' to 'Renderworld', it worked perfectly well.
I suspect that it was because I wasn't using 'captureworld' in conjuction with renderworld tween, as the docs recommend I do. Could this be the case?
Either way, I now have transparency fixed! :) Thanks for the help of everyone here, it's because of you guys that I'm able to keep going with Blitz.