ASx4 Interface debug in MSEL=111 (JTAG mode)

Hi,

could you, please, help me understand what is happening here:

I am working with an Agilex3 FPGA (fuses are on factory default, no keys programmed, etc.)

MSEL=111, so we are in JTAG mode
I am trying to debug the NOR flash interface through Configuration Debugger / QSPI Controller and SFDP page.

I have connected an oscilloscope. When I press Read button without QSPI Debug Session Activate button pressed, I see some NOR flash transactions on the oscilloscope and get back an Error 0x515 Unknown error and nothing is read in the SFDP window. So I try the QSPI debug session active way, and when I press it I get a lot of content but anything below the SFDP line in the tree structure is random at each read button press AND I do not see any NOR flash transaction at all on the ASx4 interface.
(Did it several time, so yes, I did not forgot press the trigger active button.)

So questions:

1. is this an expected behavior? Copilot suggest that ASx4 interface is not initialized when MSEL=111 and I am reading some internal "garbage"
2. If this is expected, should not the Quartus Programmer tool (which reads MSEL=111 correctly) warn me that I should not expect any meaningful output in this debug window?
3. Is there any way to use the JTAG interface here as supposed: test the interfaces for problems? if yes, how?!

(I stuck for a few more days/weeks with MSEL=111, so if that is the solution just let me know.)

Thanks,

Peter