https://github.com/zephyrproject-rtos/zephyr/pull/8535/commits: "The imxrt1050 is configured to use SYSTICK for the kernel timer, but SYSTICK cannot wake up the soc from low-power modes. Disable low-power modes on this soc until we have support for an alternative timer." "This fixes k_sleep on the EVKB version of the mimxrt1050_evk board. An earlier version of the board (EVK, not EVKB), had A0 silicon which by default did not enter low-power mode on a wfi." This patch reverts the WFI enable for further investigation post 8.2. With this patch in place together with the previous one my system is fully stable(*), just drinking a bit more power than I'd like.