When performing continuity testing on newly installed switchgear, I'm encountering intermittent failures even though all connections seem tight. What could be causing this and how do I ensure reliable testing?

I'm working on commissioning a medium-voltage switchgear panel in an industrial plant. I've checked all bolts and connections with a torque wrench, and visually inspected for any loose wires. Using a standard digital multimeter set to continuity mode, the test sometimes passes and sometimes fails randomly. I've tried cleaning contact surfaces and ensuring proper grounding, but the issue persists. Are there specific environmental factors or test procedures I might be overlooking?