I am on Lubuntu 18.04.2 and encountering a similar issue. This only started after upgrading TV to 14.1.18533. I am not sure how to activate my device as I think my email has been confirmed.... starting the service did not fix the issue. I checked port 5938 fwiw nmap -p 5938 teamviewer.com
Starting Nmap 7.60 ( https://nmap.org ) at 2019-03-02 17:29 EST
Nmap scan report for teamviewer.com (22.214.171.124)
Host is up (0.10s latency).
PORT STATE SERVICE
5938/tcp filtered teamviewer
Nmap done: 1 IP address (1 host up) scanned in 1.41 seconds
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