I have solved my GPS problem by downgrading to kitkat. I was planning to send in my phone for repair but tried this as a last resort. now maps is finding and holding GPS.
It doesn't work as well as before and loses GPS signal on a regular base but it finds it again also, under android 5 there was no GPS. So this is better.
I've got the same problem with my A86. The GPS doesn't fix even if I use the A-GPS function. I'm actually with the latest firmware also. @Marc_QRY : to be back in a KitKat firmware make your GPS working? I should downgrade too. What did you do to downgrade?
A downgrade is the same as an upgrade and yes after the downgrade the GPS works not very good but it works. It loses the signal on a regular base but it also finds it again, under android 5 there was no GPS.
You perform a downgrade same as an upgrade and after the downgrade maken a cache wipe and a factory reset.