Would the 0.56 be less if it was having trouble extruding? I guess maybe depending on the problem. If it only pushed through 79mm instead of 100, then it would still be 56, I would think.
Here’s a silly question, can you confirm that you have the esteps set to 200? In the LCD you can check by Control->Motion->Esteps/mm. The default in Ryan’s firmware is 200. If this is set to 160, then it would cause the 79mm.