We run into problems with some applications that inject key events because our process is running at a higher Integrity level, and Microsoft blocks such applications from receiving injected input from lower Integrity level applications. That's my guess for what's happening here, particularly since it was a Workstation 12=>14 break.
You can sometimes work-around this by either:
(1) Converting the VMs to shared (so that we'll open a lower Integrity remote console into the VM, rather than a higher Integrity local console, albeit at the cost of losing some features/performance)
(2) Launching Workstation or the 3rd party app as Administrator (so that they start with elevated Integrity). (Various combinations of which one to start as Admin might work here depending on the application.)
(3) Disabling System Integrity protection (although that puts you at increased security risk)
(4) Upgrading the to the latest version of Win10/Workstation
I don't recall having seen the keyboard version of this before, but a mouse event version was seen in this thread which might have some other quirks/suggestions:
Re: VMware workstation 14 Pro loses Mouse Focus
Re: VMware workstation 14 Pro loses Mouse Focus
We're working towards resolving these issues in a future version of Workstation, but getting all of these cases is more of an architectural problem than a simple bug at this point, so I can't predict a timeline for it. There might be something simpler we can do for this specific case as a bug fix in a minor update, but I can't make any promises.
