The only answer Brave has for us is that it can happen and it’s something to do with their system reconciling ads. That said, they have had issues, like a couple months ago a lot of people ended up getting like 0.02 BAT instead of full payment and Brave announced the issue and sent out an extra payment. They also then asked anyone who didn’t get the full payment to submit Support Tickets.
So it is a variety of things going on. I have reached out to Brave and am hoping they can get back to me on more details or at least see about getting better on resolving problems. For now, it’s just a minor inconvenience. We do get all of our BAT, it just can get delayed compared to when we want it.