Random problem with "navigate to"

When using Locus4 with brouter data downloaded, I periodically encounter a problem with "navigate to" function (used to measure real distance to specific place - just as in mapy.cz). Locus4 just refuses to create "navigation", when starting point is unknown for him.

As I observed, it usally happens when I was near the road, eg. on camping place, which seems to make sense, when you eg. camp in the middle of nowhere. But trying to move startion point to road (as on attached screenshot) leads to nothing, no matter how to precise I tried to be.

When Locus4 refuses to navigate, then it is impossible to force him :-(