I am using version 2.3.
In the heatmap the enter button is 0% while I am pretty sure that I pressed the enter button at least once today. 
Also pressing the enter button in the heatmap is not solving the problem.
While the number of keystrokes is increased by one.
It would be nice it this is solved, also alt and ctrl are not displayed correctly but is counted.
It’s more than just enter and those other keys that aren’t logged for me on Gentoo Linux in the heatmap, left and right ctrl, alt and shift keys, tilde key and enter keys are’t showing up/updated on the heatmap.
It would be nice if a numpad was also showed on the heatmap too, the numpad keys get added to the other number keys on the heatmap either.