always returns 0, but it works perfectly in build. Same problem with Vector2 values. With Buttons works correctly.
If I downgrade to 1.0.2 it works perfectly in player and in build.
I filed a bug report about this (some inputs receiving a value of zero when read a second time). Unity marked it as a duplicate of the following issue (linked), so I voted on that issue to be fixed. You should too if it’s causing you problems (in my case I’m postponing upgrading to newer versions of Unity and the Input System) else who knows if Unity will ever consider it important enough to be fixed.