The way PrePoMax displays pretension symbols has changed in this version. This is the old approach: Diference between variable Displacements and Disp&Def for postprocessing deformed results? - #24 by FEAnalyst and this is how it should work now: Diference between variable Displacements and Disp&Def for postprocessing deformed results? - #34 by Matej
Other posts in that thread also show how it’s handled in Abaqus and why such a change was implemented.
Of course, my tutorial on pretension was made in much older version.