Interlock that heaves or sinks rarely has a paver problem. It has a base problem. Every winter in Ottawa the ground freezes, thaws, and refreezes many times, and water trapped in a thin or loosely packed base expands as it freezes, pushing pavers up unevenly. When it thaws, the base settles back, and not always where it started.
The fix is built in on day one. A walkway or patio needs to be excavated well below the finished surface, and a driveway deeper still, because it carries vehicles. That space is filled with crushed granular, typically Granular A, placed in thin lifts and compacted with a plate compactor between each one. A base compacted in one thick pass looks the same on the day it's finished, but it settles unevenly within a couple of seasons.
Edges matter as much as depth. Without proper edge restraint, pavers slowly creep outward and the joints open up, which lets sand wash out and weeds in. Joints finished with polymeric sand lock the surface together and shed water.
Finally, slope. Every patio and walkway should carry water away from the house at a gentle, consistent grade. Water that pools against your foundation or sits on a flat patio is water that ends up freezing in your base.
When you're comparing interlock quotes, ask each contractor how deep they'll excavate, what base material they'll use, and how they'll compact it. The answers tell you more than the paver brochure does.