Keep navigation on with spoken guidance with device in pocket

[mlun58]

I've started to use walking poles, and would like to just put my Android in the pocket and listen to spoken guidance via my earplugs. But it seems as if either navigation stops when the pause screen kicks in or the spoken guidance stops or both. I just hear one or two instructions, and then it is silent. When I take up my device and turn screen on, I have to tap the route and start navigation again.
Have I missed some settings for this, and is it a Locus issue or an Android issue?
Thanks 

[Menion]

Hello,
this really looks like a very aggressive battery optimization on your device. If you need to start navigation again manually, this may only mean that the system killed Locus Map while on the background.

Suggest checking this nice website and check tips for your device. Hope this helps.