This one sounds obvious, but stick with me. Open your brine tank (the big plastic bin). Is there salt? Really look.
If the salt looks like a solid brick of cheese, you have “salt bridging.” If it’s just a mushy sludge at the bottom, you might have “salt mushing.” Both mean no softening happening.
Grab a wooden spoon (yes, really) and poke the salt. It should crumble into separate pellets. If it doesn’t, your system is likely starved and useless.
How do I know if my water softener is working properly?