Landscape Paint tool not working properly


I’m new to Unreal Engine, and having a few issues with landscape painting even though i’ve followed tutorials.

When I paint it sometimes takes 10 strokes or more to actually paint what i want (e.g. dirt on top of grass texture) - sometimes it won’t even let me at all, and nothing happens.
I’ve tried playing around with brush size, strength and falloff - nothing works.

Also, it seems like it only allows me to paint in tiles / a grid, so it doesn’t look smooth at all. I’ve attached a picture of a dirt road that I’ve tried to turn smoothly, and spent some time on it, but it’s impossible to make it more smooth than it is now. On the videos I’ve watched, painting AND sculpting looks much smoother. They get instant feedback, can sculpt and paint in small details and are not restricted to what feels like a grid to me, that I have to paint onto.

As you can see, the above is not smooth even though I’ve spent time on it. There’s also grass some places where there is supposed to be dirt, but I cant seem to change this.

It’s like this for the entire level, but some places are more difficult to paint for no apparent reason?
This is the master material I’ve set up. Very simple, so it should not be a problem. Right?

Would really appreciate any help I could get.