In my PP_11.3, when you set a 'Diffuse' texture, the 'Image Map' whatsit that pops-up attached in 'Advanced' has several options for 'Image Mapped'. Default is 'Tile' but, IIRC, there's also 'None', Clamped' and 'Alpha'. Latter does not seem to work as-is, but I've not really explored...

Spent too much of yesterday wrangling a balky texture on ported 'PMX' model, as its 'sky island' 'owl' plinths showed black. Finally found I had to set that texture's pop-up's V-Scale to '-1' from 1.00 default...