Lily distance tracking incorrect

the distance tracking on my Garmin Lily has recently started being wildly incorrect. 
up until 2 weeks ago it was fine then I bought a new phone and it’s saying I’m running much further than what I am and the pace therefore is very inaccurate. 
I’ve reset the distance and gps setting on phone and repaired the watch with new phone ect. I have read through so many forums ect to try and solve this and am having no luck. Has anyone had this issue? Coincidentally a family member also has Lily and said this started happening recently to them too so now I’m unsure if it’s a new phone issue or the actual software or something in the watch!! HELP?!