MDK fails to download flash on STM32H753 with ST LINK/v3

I have STM32H753I-EVAL2 just out of box, no changes made.

www.st.com/.../stm32h753i-eval.html

Built an example app from ST package (if it matters, LwIP_HTTP_Server_Raw)

MDK 5.26.2 debugger sees the ST-LINK/v3 on the board - but cannot erase and write internal flash.

Erase and program progress runs quickly but verification fails. All flash bytes read as FF.

Then I connect with ST CubeProgrammer and it successfully downloads the program  -

after a thorough reset (power and debugger cable disconnected & reconnected). Just pressing reset button on the board does not help.

Without power off, after MDK failure, Cube Programmer also cannot connect, and the on-board ST-Link cannot connect (puts a error message file on its USB drive).

When CubeProgrammer can connect, it shows that the memory is partially written. Spans of valid data interleaved with spans of FFs, But not all FFs, as the debugger reports.

Also, after the debugger reports that the flash was erased - it is not (checked with Cube Programmer).

The MCU and size of flash (M7, 2 MB) is detected correctly.

Is this a know issue with STM32H7 or this board, or I need some extra setting?

Thanks in advance,

Pavel A.