contributors-summary last updated does not display correct information

We have spotted that the code that lists the number of updates per
member of staff has a bug. If someone has added a comment to a Wiki
space, the date last updated is always 'a minute ago' even if they
haven't logged in for months. See attached image with highlighted
rows.

The code we are using is:

{contributors-summary:columns=edits,comments,labels, lastupdate|scope=descendants}

Is this a known issue in 3.5.16 and is it fixed in new versions?