Here is where the problem lies.......... aside from "RTFM" ( read the freakin' manual )
Long time ago, we do not carry GPS all day long, now many of us do, inside our smartphone. Well I always turn my LOCATION off.
My first GPS able phone was the famous Nokia N-95 in 2007. Poor sensitivity back then, but useable if open sky. Phone cost a fortune.
Fast forward today, even el-cheapo under US$150 branded Samsung smartphone has GPS chip.
Rewind a bit some years back before 2015. Many smartphones OEM get smart, no GPS no problem, lets call it A-GPS ...LOL.
Cell phone triangulation was used as A-GPS. Then come wifi hot spot able to give positioning data.... yada yada, I do not know what they call that feature. So I think many people today will think that as long as their cellphone shows signal, it surely has GPS positioning too.
So those lazy to RTFM, will assume that GPS is like air we breath, no matter where you are, it will always work ..
and accurate.
I think its the same as the word TURBO, which to many means FAST, while not knowing the true mechanical meaning of it , or how it works.
There is a funny story. I was at a camera store one day. The come a guy who is was warranty claiming a GoPro remote control to the shop, he said "This remote control is defective, because it does not work underwater !!" LOL.
So, if I were the OP :
"I will sue 3DR , I will email my lawyer from my waterproof-housed iPhone 6S..... while I am 3 feet underwater in my pool relaxing myself, I will get a Turbocharged response because 3DR will piss in their pants !! "