Thankfully this has been fixed in 5.2b Dec patch, maybe even in an earlier patch!
Admirals would not send 100 ships to chase 1 ship. The fleet would break off a flotilla or a squadron to interdict a lone ship. The flotilla or a squadron would seek out the weather gauge. Anyone with a shred of Navy experience knows this. Total fail on PI!
Eh? You are the commander here and you order your ships to move as you see fit. If you are the one that commands that your entire navy over several hundred ships move as one then you are the admiral with no shred of navy experience.
Paradox gives you the tools. the OP used them poorly.