I'm using Thunderbird 52.9.1 on my laptop, which runs Linux Ubuntu 18.04. At work, I installed Thunderbird on a desktop running Windows 7. Thunderbird (with the Lightning add-on) works great there, but ever since doing that I can't get Lightning to sync up on my laptop. Everything else works fine, and it shows no indication that the synced calendars are unable to connect with the server, but none of the changes made from the work desktop are reflected and I can't add or modify existing events or accept invitations to new ones from my laptop.

UPDATE: Two changes have taken place without fixing the situation. First, I uninstalled Thunderbird from the desktop computer, and second, Thunderbird has updated to version 60.2.1 on my laptop. Neither change has impacted the functionality of the calendar on my laptop.