BackstopJS: Components failing tests when mismatch percent is near zero.

Our mismatchThreshold is set as follows: "misMatchThreshold": 5, however when the tests run certain tests fail and say "isSameDimensions": false,.

Here’s an example of some screenshots where the tests should pass but don’t seem to.

Here’s the output result from the report:

Report: {
  "isSameDimensions": false,
  "dimensionDifference": {
    "width": 0,
    "height": -1
  },
  "misMatchPercentage": "0.48"
}
Threshold: 1

This happens on around 8-10 tests, intermittently. Are we missing something, or is there a way to turn off the isSameDimensions property? Is this expected?

Thanks in advance for your advice.