The HEX file must contain data targeted for the correct address space.
Make sure that your configuration file and your HEX file are using the matching address values.
For example, on the nRF5340 SoC, the XIP address space starts at 0x10000000 (and it can start at this address for the nRF54L15 SoC), at the nRF52840 SoC, the XIP address space starts at 0x12000000, and at nRF54H20 the XIP address space starts at 0x60000000.
Tip
When using the nRF Connect SDK and the Zephyr RTOS, the correct memory addresses can be handled semi-automatically using Zephyr's Code relocation nocopy commands.