Not all shave soaps are created equal. Some soaps with a glycerin base are a hard soap (like a bar of soap) and can't be easily scraped off the tub or puck. This means that sometimes lathering is more challenging- it doesn't mean the soap doesn't work or that you have an inferior product. Ultimately, it's a different soap making process and requires a slightly different lathering technique.
Here's a video on how to bloom your shave soap.
The best and easiest way to lather a hard soap is to bloom the soap.
1) Simply add hot water to the soap tub, or if its in a mug, add the water to the mug.
2) After about 30 seconds to 1 minutes, dump the water out. Alternatively, you can use this somewhat soapy water as a pre-shave treatment.
3) Using a shave brush, begin swirling the brush on the hard soap. The brush should be slightly damp but not sopping wet. It's easier to add water than take away.
4) Finally, take your time. If you extend the amount of time swirling your brush, you may find the lather will reach a more dense state and will be perfect for your wet shave.