Because PureCloud is on a "continuous release" cycle, the design is to continuously push updates into the cloud and, in the case of installed applications like the Softphone, to the installed applications. There is no defined release cycle, and with the incremental updates there is not necessarily a defined "latest release" to post.
The system is behaving as designed - you use the latest posted install package to install the software locally, and PureCloud automatically updates that software as needed. Eventually another install package is built, gets posted, and the cycle starts over again.
That's how continuous release works for all of PureCloud - you just don't see it most of the time, since it happens in the cloud rather than an installed application.