I did happen to find my address book there however the .xml file was blank. Luckily I have a good backup and attempted to restore the file with no luck. I did perform the upgrade to the server but I am still struggling getting the address book, users, groups, and permissions to be restored.
I have a ticket opened to attempt a restore of the address book.
The data.xml file has all the information about the available address books, user groups and permissions. If that file is blank nothing works. I now backup that data directory anytime changes are made to my address books just to be safe. From my experience if the data.xml file is valid, its a simple copy and paste of all the files in the data folder, then restart the RU server to restore the previous address books and user settings.
The issue with auto-import that caused RU Server service to hang/freeze was indeed fixed back in December update. Since then there was one more update, so the current server version is 18.104.22.168. I recommend that you update your server to that version.
As Steven suggested, it is a good idea to backup the server data folder in case of failure. We didn't implement a backup option on the Server because there are numerous back up tools (including built-in Windows backup options) that can do the task much better. The folder that you need to back up is the "data" folder which itself is located in Server installation folder.