When "Fill in Rank Drop Gaps in Charts" is enabled within your settings, this will fill in any gaps in your keyword chart to smoothen the progress line out.
Not filled in:
As you can see from the screenshot, the gaps or the times that it fell out of the Top 100 position are filled in. This does not mean that your keyword ranked in the position that is showing. The chart only linked the gaps from the last time it ranked to the next time it ranked in the Top 100 position.
If you would like to double-check the chart's accuracy, we recommend that you double-check the history. You may export the history here.
We hope you find this helpful! If you need any further assistance, please contact us and we'll be more than glad to help you out.