You tried the latest version?.This version throws a lot of errors into the log in backend after importing the previous data. All of them about database operations. I prevent to do not use it until @lgokul could verify and check it. I believe that he has only tested the installation, but not when using data or when importing the JSON from previous versions.
1.- Uninstall the plugin from the wordpress dashboard.
2.- Then install it again and if it asks for a license everything is fine.
3.- Import again and see if the error persists.
If it does send me your logs.
Since this error was fixed in previous versions.