What is wrong is that B-sources do not implement temporal tolerance (TTOL), because it was not anticipated they would be used for this purpose. KSKelvin, in a recent thread has suggested some workarounds that do not involve stop time or maximum timestep.
I found it for you:
TTOL device to Interface analog and digital - QSPICE - Qorvo Tech Forum
This thread also has additional insights.
TRIPDT and TRIPDV Parameters - QSPICE - Qorvo Tech Forum