Why does an upright box slide? Road transport assumes 0.8 g forward and 0.5 g sideways (CTU Code, Chapter 5), while on an unswept surface the friction factor is at most 0.3.
Put the box on a clean, level, non-slip base; for clean rubber the factor is 0.6 (CTU Code, Annex 7). Close the side gap, but do not crush the box or press the lid.
Trial a short route with braking and a ramp using the real load, and record orientation and damage at delivery.

