I noticed that after version 15.6.6 when i opened my sygic the screen would flicker (black and white squares would flash, and when moving the map i noticed that streets where flashing as well when moving into green or water areas).
It wasn't something that wouldn't let me use the app, but it was really annoying.
I'm using Samsung Galaxy S5 octa-international version (G900H) with stock rom for Argentina and root with Phillz CMW.
I just tried a solution from someon who had a similar bug, you have to go to Sygic/Android folder and open the core3d.ini file.
There i had the following:
0=CRendererGL2 ; OpenGL 2.0 (OpenGL ES 2.0) based renderer
1=CRendererGL ; OpenGL 1.5 (OpenGL ES 1.1) based renderer
And what i did was change de OpenGL by changing the 1 and 0 values into
1=CRendererGL2 ; OpenGL 2.0 (OpenGL ES 2.0) based renderer
0=CRendererGL ; OpenGL 1.5 (OpenGL ES 1.1) based renderer
Anyone knows if it changes something internally? I hope my phone doesn't overheat or explodes if it is possible haha.
But well, right now all the screen flickering stopped, so you can say it's a fix, even though i don't know what changes using another OpenGL.
Hope it helps!