I think they came with rounds back in the day, which is why John Entwistle got through so many of them - he'd snap the strings but couldn't buy replacements so had to buy a whole new bass.
My Longhorn came with rounds when I got it new in 2005. Very distinctive tone, a hollow twang far growlier than you'd expect. I was never able to play it live as it refused to stay in tune. Useless tuners.
I also have a Hofner Ignition Violin bass. Contrary to earlier posts I find it to be rather limited in what it can do - luckily, that big dull thump is just perfect. Massive bottom. Mine's wearing Hofner flats. No issues with tuning that I've noticed. There is some neck dive but it's really not a concern as the whole bass weighs about as much as a tissue.