How can I get ViewRanger to keep recording my track on my tablet even when the cover is closed?

Question

I have a Samsung Galaxy Tab S2 running Android 7.0 and have ViewRanger 9.0.6 (3rd September 2018 update) installed. The tablet is in a (3rd party) cover.

ViewRanger has no problem showing me where I am as I wander around, but recently I've gotten interested in having it record my track. However even in track recording mode it seems that as soon as I close the tablet's case ViewRanger stops tracking my position. It'll re-find me again when I reopen the case, "Swipe screen to unlock" and enter my PIN to get back to the app... but it has no information on where I've been while the tablet has been closed up and ViewRanger will consequently just show a not very useful straight line between the points it knows about. I'd like it to keep recording the track my position even when the device is closed up.

I've read ViewRanger's documentation here and here.

In ViewRanger's GPS settings I have "GPS Mode: Continuous" and "GPS Auto Disconnect: 30s" (although docs claim this is ignored while recording a track).

In the device settings, Location is ON with method "High accuracy" and in the Device Maintenance’s Battery section Viewranger is in the list of "Unmonitored apps" which won't be put to sleep. Power saving mode is OFF.

I'm puzzled as apps like the BBC Radio Player seem to have no problems continuing to stream and play audio while the tablet is closed up. What do I need to do to get ViewRanger to keep accurately record a track while the tablet is closed?

Bear in mind I'm pretty much an Android n00b. Lots of desktop/laptop/server experience but mobile platforms are relatively new to me (and I'm probably missing something obvious).

Update:

I queried ViewRanger's support about this and got a swift response:

This will be some form of power saving setting on the tablet, affecting either ViewRanger or Location services. The power saving varies quite a bit between devices, versions and manufacturers, which is why I can't be more specific than that.

Also check for any power / task management apps — these used to be a common problem, but are not so common now that manufacturers have power saving in their main Settings apps.

Investigations continue (although it's quite hard to research this one sitting indoors at a desk... after you change something you have to go out and walk around a bit to see if it's made a difference!)

Answer 1

I got track recording to work while the device is closed:

In the device Settings app, go to "Apps" and on the "..." menu select "Special Access" then "Optimize Battery Usage". Use the drop-down to make "All Apps" visible and then switch OFF the slider next to ViewRanger.

Source for that is here; it's the manual for a different mapping app. The page opens with

More and more users have been reporting issues with losing GPS signal during track recording when their device goes stand by...

and includes instructions on how to rectify the situation for various vendors and Android versions (the manufacturers all seem to have different ways of exposing this to the users).