For some reason, transparent PLA, especially ones touted as "high quality", seem to be among the most difficult to extrude. The worst ones for me have been a really old (4 years?) spool of Makerbot transparent, and Taulman InPLA. I have succeeded in printing both with the ZT-HE, but ultimately it wasn't even worth the trouble because the prints are brittle, with difficult support removal, and not very transparent anyway. Colored transparent from JustPLA has worked much better for me.