We have developed a board with an Intel x86-64 "Tiger Lake" processor. We have installed the Intel Slim Bootloader on it, in SPI flash.
We are connecting to the board using a MIPI60 socket, using an LA-3500, LA-4590 and CombiProbe 2 MIPI60-CV2.

When we power up the board on its own, TRACE32 can connect to the board successfully, and we can debug software on it.

The processor board can connect to a second board (with no CPU on it) via a multi-way connector. When we plug that board in, TRACE32 can no longer connect to the Tiger Lake CPU.

When I start TRACE32, it initially reports "power down". I plug in the MIPI60 connector and it then reports "system down". I run the command SYSyem.DETECT TARGET. It still reports "system down" and logs the following error messages:-
Found 1 topology.
No CPU topology found!
error occurred, id='ERROR IN DETECTING TOPOLOGY!'

We assume that some signal on that multi-way connector is interfering with the JTAG connection to the CPU. But I cannot find any documentation that shows these error messages.

Has anyone seen this behaviour before? Are there any signal lines that we should be looking at in particular?