Root shouldn’t interfere with WhatsApp. I run FPOOS, and WhatsApp runs fine, including a database file that’s been inside four different phones. You also copied over the correct file. The group chats appear because they’re stored on the server, so your phone just downloads them from there.
First, let’s be sure the copying process worked properly: when you look at the database file in your file manager, is the file bigger than 0kB?