I know this post is dated, but I have a question as I am experiencing the same issue. I've read through this whole post and keep seeing "if it was previously installed on the device".
I recently purchased me a new phone and gave my older phone to my friend. The old phone was factory reset before I gave it to him. I invited him to play Raid...he has never played before. He is now Lvl 19 and I haven't gotten the first reward, nor is he even on the list of refereed friends. So is it because RAID was previously installed on that device, (even though it was factory reset and now belongs to someone else now)... that the referral system is not counting him as a refereed friend? If so, that's pretty lousy with the amount of recycled and used phones being sold on Amazon and Ebay.
Please...any response woul dbe greatly appreciated.