But if you would have also not voted because of issue Y or Z are also dealbreakers, then you'd be a multi-issue voter. If candidate A believes Y and Z, but not X, candidate B believed in X and Y, but not Z, and candidate C that believes in X and Z, but not Y, so you just didn't vote, it would be clear its 3 different issues that you care about, but for each candidate, it would be a single issue why you aren't voting for them. Would that just mean you are a single-issue voter for 3 different issues?
But if candidate A believes in Y and Z, candidate B believes in Z, and candidate C doesn't believe in any of them in a particular election, in that case X alone would mean not voting for any of them.