150 tracks without knowing the range of their navigation radar systems doesn't say much. It's hard to put more than 150 objects in a 5-10NM radius. Since it's a navy ship the nav radar is probably more powerful, but still, it's not like a 200NM range air-defence radar. I'm guessing they spec-d the system with incoherent requirements, and either the contractor that won went for the cheapest working hardware without asking too many questions, or maybe they took an old system's spec and asked for an incomplete upgrade... or nobody wanted to go to their boss saying the system didn't work because of some badly written spec or badly managed contractor and we need more money, please ? That would track with leaving the system badly working like this without even having some face-saving 'we're trying to work it out with the contractor right now'.

Or, most likely, normalisation of deviance. The system came at first with so many bugs and problems that when they got it in some stable state, they'd got so used to work around the bugs that they kept on doing that. Look we already put so much effort in this, what's a bit more? Yeah, we're quite happy with the system, at least it doesn't crash every hour like when it was delivered...