It seems really weird they don't like fish baits ?
In this country they don’t. I know in Australia and other places they do. I suppose it depends on what’s locally available.
Very rarely, including last year, here we had a real glut of medium sized pack fish about 5-7lb and they must have been competing for food because that’s the only time I’d heard of them being caught on mackerel.
But at best it would be a fluke catch - far better to match the bait that works to the fish rather than wasting your time with mackerel etc because ‘it might work’
Imo the order of effectiveness would be peeler, squid and ragworm (which can work well but seems to be a bit area dependent).
Or indeed anything crabby including hardbacks.
I wouldn’t be particularly confident using prawns in this area (unless they were live prawns, which is deadly), but I know people have success on them in other areas.
I’d definitely avoid fish baits though.