In De la Cruz's case, Democratic-aligned challengers argued that seven of the PSL's 19 presidential electors named in the paperwork were registered as Democrats, violating a political disaffiliation provision which prohibits minor-party candidates from being registered with a major party within 30 days of a primary.
This might seem like an unreasonable requirement, but it belies a lack of honesty in the campaign. You can't just decide you're going to fix everything wrong with American Democracy within a month. You can't just do nothing for four years and then show up just in time for the primaries to pretend like you're a viable party.