pdflatex rendering fix
Saving the graphic as an eps did the trick, hurray. Haven’t tried any tests with gradients containing transparency yet but those seem to be rendering fine in the final pdf (so far anyway) — though overleaf does seem to have issues rendering them in the online preview, so keeping an eye out.
Hmmm transparency + gradients seem to be too much: one or the other it seems?
Second night this week of being jolted awake by dreams in the 3-4am region.