Without knowing the specifics I'm not sure what exactly is going on. It could be you don't have enough soap or more likely you need to add more water or even you might not be working long enough to build the lather up. I'm really don't know. I do know that if you try to build the lather on top of the puck you will continue to load the brush as you try to make the lather which will make it a pasty consistency so it would be better if you didn't do that (that would be alright if you want to build the lather on your face, a.k.a. face lather but if that's the case why not skip the mug altogether).
What soap are you using?
How long are you loading the brush for? It is dependent on the soap and if you bloom it or not but I usually load for about 25 seconds.
It sounds as if you are trying to bowl lather, is this what you are trying to do?
How much time do you take to build your lather? Some soaps do take more work than others but I don't think you can ruin lather by overworking it.
What is the consistency of your lather (e.g. watery, pasty, whipped cream, yogurt)?
What size are the bubbles in your lather? They should start off getting big bubble which as you work the lather will get smaller as the lather thickens and stiffens.
Here's a couple of YouTube tutorials on bowl lather. I know you mentioned watching some already but I thought I'd throw them in just in case someone else had the same problem.
How to Bowl Lather with a Shaving Brush - Beginner Series Ep. 9
Tips & Tricks - Bowl lathering