Disappearance of offline OSM map while walking

[silvermapper]

I have been disconcerted somewhat when walking with my 'phone on two occasions recently: my offline OSM Great Britain map disappeared.  A .kml overlay of paths and my track recording remained visible.  The map would reappear, eventually but might disappear again, too.  I was in a poor signal reception area showing a mixture of G, E, H+ and 4G.  That could not be the cause with an offline map, surely? 

[menion]

Hello,
better post some screenshot of this "empty" screen. Thanks

[Andrew Heard]

This sounds similar to an experience I reported to Menion a few months ago. It would happen once or less per day. An area of the map ahead would be totally blank except for the recorded track (map not repainted as I moved towards it). @silvermapper - is the map redisplayed after exit/run Locus? I can't find a reference to my original discussion. It may have been in forum rather than a help topic. I had one time when not even a restart worked, only a phone power cycle. It hasn't happened in last few months although I haven't been navigating all day every day. I was using Italy LoMap. The theme made no difference.

[silvermapper]

menion, Andrew
I thank you for your replies.
I must wait until the next time this phenomenon occurs before I can attach a screenshot.  I shall note to do it, however.
I tend not to exit Locus while I walk (I do not know the consequences for the track recording) and I assume the track recording is saved automatically to .gpx (that is how it is set up) should I power off and on.  I should have to start another track recording and join the two, ultimately, in that case.   

[Andrew Heard]

If you exit (tap back button twice) any track recording is preserved and restarted when you restart. Good feature. While cycling and the map started disappearing, with practice, I could exit & restart within ~30s, and all without crashing

[john_percy]

Does it reappear if you zoom in or out and then back again? I've had that sort of behaviour on changing offline maps or themes before, and again recently (but not reproducibly).

Sent from my XT1039 using Tapatalk

[Andrew Heard]

In my case (Italy LoMap), zooming/ panning/ change theme/ anything else I could think of, made no difference. Once I moved into an area where nothing was drawn there was no option but to exit/restart of the app. In one case only a power cycle of the phone. It has not happened in last 3 months with Australia LoMap.

[menion]

Hmm similar problem happen to me few days ago during implementing new animation feature for moving map ( should be visible in latest Beta in track editor after selecting stuff like "remove before" etc.). I found small problem that was caused by incorrect zoom system. Pinch zoom temporary disable reloading of map tiles till zoom is finished and here happen that even after releasing fingers, zoom stayed unfinished. Not sure if same happen to you here, but if this happen, try to remember if you were using pinch zoom before ( or something with zooming by fingers ).

[silvermapper]

Andrew
I thank you for your advice regarding being able to exit and restart Locus Map without losing the track recording, which I verified on a dry run.  I should have tried that much earlier.
Now, to the disappearance of the offline map:
I set out on my walk today and saw again the lack of map after an hour when I pushed the 'on' button to check my location.  There was no network signal at this time.  It is fortunate that I have, as an overlay, the public rights of way that I walk and check.  I continued to walk for another hour.  I noticed at times the 'phone showed 'H' and a reasonable signal.  Then it clicked: I touched the 'Maps' tab and discovered my offline map was deselected!
I shall try the newest version of Locus Map when the apparent issues with Android 4.4.4 are resolved and report, accordingly.
One further comment regarding the preservation of track recording: I had forgotten to plug in my power pack when I saw the battery was low.  It powered off when I looked next at the screen.  I am pleased to report that the track recording was present, still, when, having plugged in the power pack, I could power up the 'phone after a few minutes.   
 

[Andrew Heard]

@silvermapper - I should mention again, in my case, I was using offline map in airplane mode.
@menion - in my case, I was never manually zooming/ panning the map, I was cycling in Navigation mode/ Hold Map Centre=on. Problem occurred maybe once or twice a day over period of 7 days touring  four months ago, but then no further problems since that time. I don't think it was related to any change of Locus version.

[freischneider]

I had that problem too. But only with Android 4.4 Well I have 7.0 and everything is good.

[silvermapper]

I omitted in my reply yesterday something to which I wish to draw attention: I had not taken action previously to exit Locus Map while track recording because what I construed to be a warning appeared:
"Do you really want to EXIT?  All active processes will be terminated.  No data will be lost.  STOP & EXIT".  I understood from this message that my track recording would stop but be saved, meaning that when I restarted Locus Map, I should have to start a new track recording, too.  Am I alone in interpreting the message in this way?

[Andrew Heard]

I have track recording automatically start when Locus is started. If you exit when track recording is active then re-run Locus the same track recording automatically continues (for me).

[menion]

Hi guys, quite long topic and I'm little lazy today to read it, sorry. Anyway is problem with empty map happen in latest 3.26+ version as well? ( maybe wait also on new 3.26.2 version that comes today, there was also one small issue in case of loaded KMZ content ). If @silvermapper, you will be able to simulate this problem with latest version, let me know. I may prepare some special version that will print us more info into logs. Just to be sure, try to simulate it with disabled all possible shading, WMS maps or overlays. Points & tracks should make no difference. Thanks