Here we study the stability of charge order in the kagome metal ScV6Sn6. Synchrotron x-ray diffraction measurements reveal high-temperature, short-range charge correlations at the wave vectors along q=(13,13,12) whose interlayer correlation lengths diverge upon cooling. At the charge order transition, this divergence is interrupted, and long-range order freezes in along q=(13,13,13), as previously reported, while disorder enables the charge correlations to persist at the q=(13,13,12) wave vector down to the lowest temperatures measured. Both short-range and long-range charge correlations seemingly arise from the same instability and both are rapidly quenched upon the introduction of larger Y ions onto the Sc sites. Our results validate the theoretical prediction of the primary lattice instability at q=(13,13,12), and we present a heuristic picture for viewing the frustration of charge order in this compound. © 2023 American Physical Society.