On what part?
The CM0 and CM7 have some issues with single-step.
Is code running out of QSPI?
Do you have Ethernet in your system, or is this more of a Default_Handler thing?
Debugging typically doesn't stop the rest of the system running, if the Ethernet is getting interrupts faster than your response time, it can be the next thing to execute.
I'm not sure some of these things are bugs, but rather that you're at the edge of the universe, the debugger is the fractional use case for the core and transistors aren't wasted to make things perfect under all conditions.
Try code without optimization, this confuses the debugger less as it tries to resolve assembler to C source lines.
Use a disassembly view, step those, and review a static listing file.
Instrument your code to better understand dynamic behaviour and flow.
#MatrixGlitching #Milliways