The erroneous configuration in the tx_initialize_low_level.S is this:
LDR r1, =0x40FF0000 // SysT, PnSV, Rsrv, DbgM
The tx_initialize_low_level.S file is generated upon selecting ThreadX 'Core' in the STM32CubeMX v6.15.0, and the above line is thereafter never changed. Specifically, upon enabling 'Enable BASEPRI support' and selecting a very common value of 5 for the TX_BASEPRI_VALUE, the above line is not updated accordingly. Not syncing the SYSTICK IRQ priority with the TX_BASE_PRI_VALUE of course leads to a system failure.
This issue can be duplicated by creating a brand new project with STM32CubeMX v6.15.0 and it can be seen in the sample projects included in the Applications/ThreadX in the STM32Cube_FW_U5_V1.8.0
