Galli Strings UXB910C Ukulele Bass Str.

I have now fitted these strings to both my Uke Basses having tried all the black white and red other makes.. you know which ones if you are reading this.
These flatwound strings are the first that actually pitch correctly up and down the fretboard. The suit the sound I wanted as I play fender Jazz bass with flatwounds but on the Ukes, the sound it earthy, organic and punchy... all in one.
I have a Kala acoustic and a Mahalo solid body Uke which I play in a Celtic band. The sounds leaves the audience with dropped jaws, as the look for the hidden double bass, and I also use in rock bands and the solid bodly sounds remarkably similar to my "much heavier" fender jazz.
There is now no turning back from these. I can only recommend you try some.
Yes, they are pricey, but they last a heck of a long time. just keep them clean and wipe down after each gig.

After trying out many different ubass strings (Thunder Reds, Thunder Browns, stock white, roundwounds) I think I found the best ones for my likes.
The strings are super smooth, allowing for very easy sliding. Absolutely no sticky fingers issues so far, significally better than the roundwounds and a world apart from the polyurethanes in this regard. I only play with roundwounds on my full scale basses, so I appreciate the flatness :-) Note that the tension is pretty high & not the best for bending. I'd say that's it is slightly higher that the roundwounds & much higher than the polyurethane ones.
On my Kala Nomad the tone is not as 'uprighty' to my ears as the polyurethanes, giving the ubass a bit more of an acoustic bass sound. Also, much less overtones than the roundwound strings, with the fundamental being more present. There's also zero contact noises (right when the finger touches the strings), which can be an issue with the polyurethanes.
The tuning didn't take long to settle, but some clipping of the end of the string may be needed since they are a bit long.
All in all, best ubass strings I've tried so far.