I've had this issue on every distro I've ever used, on every version of Plasma I've ever used (this even dates back to the KDE 4 series). In short though, closing the lid on my laptop disables my touchpad. The issue is a little worse on 5.13 though. In previous versions if I locked my screen before closing my laptop everything was fine, however in 5.13 that trick no longer works, leaving my touchpad completely disabled. If I check synclient before and after this occurs, the `TouchpadOff` values remains the same, '2'. I know at least one other person had this issue (in response to a post I made about a year ago, here viewtopic.php?f=289&t=140825). Because that post is a year old, and since the new version of Plasma made some changes, I thought it warranted a new post.

As there was a little confusion in my previous post, I'll leave some clarifications here.
The issue seems to be that my touchpad does not get re-enabled when I open my lid again.
This issue only occurs on Plasma.