Hi John,
Tried 2021.2, makes no difference.
Tried both SD and micro slots, same behavior.
Second board/module combination has another brick supply.
Tried to boot hello_te0807 from QSPI and it works. After that tried my own design booting from QSPI and it also works.
So for some unknown reason SD refuses to boot while there is no problem with QSPI with the same .bin files.
I decided to use the QSPI from now on, can live with that.
Thanks for your support,
Boki