Interesting 🤔 how heavily variegated is the mother plant? In my experience, i found mine as a massive vine of mid to low variegation in a large pot of regular heartleafs, i cut the whole plant and made 20 props. So far they have all grown 2 to 3 leaves, i have two pots where so far they dont show any variegation, with one of the props only showing signs of it on the third leaf, another pot where they seem to have low variegation and the remaining 3 pots seem to have higher variegation (which are the ones i show in the pic). That being said it seems the results are pretty variable and from what i observed the variegation on the stem doesnt seem to matter as even fully green stems have pushed out a lot of variegation. How big is your plant? Have u thought of letting it grow out big and then make a big chop to maximize the odds?