Host 13.0.6447 installed - try to add to account - TeamViewer wants me replace one of my full instal

Update - from my office using one of the full installs I was able to add that troublesome host to my list of computers. Why it wouldn't let me do that at the customer's place is beyond me.

Hello Community,
I've just tried to install TeamViewer Host 13.0.6447 on a new Windows 2016 Server.
Installation seems to be fine until I try to add this new host to my business account (3 installs of FULL version allowed).
TeamViewer asks me to replace one of the 3 devices I use for remote support?!?
Tried un-install, re-download and re-install to make sure we're really talking host version of TeamViewer here...
I already deleted a few old HOSTs from my list of computers (there's a limit on that number, too) that I no longer support, but that didn't solve the issue so far.
See screenshots below.
Any advice highly appreciated, that's the first real issue I encounter with TeamViewer.
Thanks in advance,
Udo

TeamViewer Host Issue #1.png

 

TV asks to replace one of my Full InstallsTV asks to replace one of my Full Installs