- I see you use LDAP. So you must first download the LDAP plugin for 1.18.x, place that in the plugins folder, and then import the db and upgrade. The updated plugin is needed during upgrade so it can convert the accounts accordingly.
- Do you have any attachment storage plugins installed?
- Read #1
- Sounds like your Agent account doesn't have Department access to the rest of the Tickets. Add yourself to all Departments and see if you see all Tickets.
Also, I wouldn't update string from the config file. I'd simply copy over the entire config file and update just the db info if different.
Cheers.