I have also encountered this problem with a project that ran perfectly before, within or without the debug environment. I spent a few weeks building i2c and QSPI functionality, which all ran fine in the debug environment. But when I restarted the board without the MCUXpresso debug environment, it hangs (no more blinking led)!
Note that I moved from a managed linker script to custom script, and have just noticed that the "Semihost Console" and "UART Console" are both grayed-out in Quick Settings >> SDK Debug Console. I added the suggested hard-fault handler, but that has not helped.
I'll be back to fight on Monday - have a good weekend,
Denis