Many variables in play. First I'd consider Hard Water. This keeps soap from lathering, instead makes something called scum. It's easy to eliminate this variable by trying distilled water. Your brush, the motion you use to load, the amount of soap you gather into the brush, the bowl or mug having texture inside, or the amount of stubble if you face lather.
As a new shaver reducing these many options to doing the same thing, but changing ONE THING may help you figure out what is causing the problem. If you have several issues it will take you more experimenting. See if there is a video of someone making lather of your particular brand of soap.