I've never had a problem with any tire liners on multiple bikes. 15 years without any flats since I installed them.

It sounds to me like maybe the tire liners aren't the problem. My hypothesis is that maybe your tire is shifting on the rim, and pulling the tube with it over the edge of the tire liner. Did the valve stem on the tube show signs of shifting (not perpendicular to the rim)? Were you riding in unusually severe conditions or in a manner that might have caused this to happen? Locking the brakes on a steep downhill, for example?