Basically I transferred from one server host to another, and the playtime has transferred.

I've added the groups in the config and they are showing in game, but the roles aren't auto assigning.

What could be causing this?

Thanks in advance

PlayerRankings will just simply read the time from the data and correct it as necessary. Are you sure that the data was successfully transferred instead of being reverted to the old data?

As far as I'm aware it was successfully transferred. I had to replace the existing playtime db file and it reads all the playtimes etc correctly