Minesweeping preview bug and sweeping bug

I just had an enemy ship that clearly stands OUTSIDE of my webs, sweep the whole field!Here comes the math:

Webfield #616 at (1722,1858): 2296 mines, radius 47ly (47.91...ly truncated)

Sweeper s375 at (1745,1900)
Distance sweeper to minefield = sqrt(23^2 + 42^2) = 47.88...ly (dx=23, dy=42) 

Now either it has to documented somewhere that the ship-field distance is also truncated and the visuals have to be adjusted (as the ship is shown outside of the web), or the sweeping algorithm might be wrong.

At the same time I also have a definite bug in the sweeping preview:
I just had one of my ships sweep a minefield which was (according to the new sweeping preview) out of range for sweeping. As the calculations below show, it was actually in range and sweeping is good, but the preview is WRONG!

Minefield #389 at (1817,1950): 3380 mines, radius 58ly (58.1377... ly truncated)
Sweeper s392 at (1866,1913)
Distance sweeper to minefield = sqrt(49^2 + 37^2) = 61.400...ly  (dx=49, dy=37) 

Joshua, the game is 33942, Turn 70 to 71.