Hello Majkel,
sorry for the late response.
It looks based on your screenshot, that the GPS caused a shift of "active point of navigation" somewhere back along the track. The solution should be to force navigation using a nearest point on the track > for this, try to open the navigation menu > "Nearest point".
Anyway, this should not simply happen and when. the app should fix this in a few seconds automatically, weird. Is GPS turned off during this pause when the screen is turned off?