I have sucessfully run the QSPI_EXAMPLE_XMC45 demo project on the Infineon XMC4500 CPU45A_V3 eval-board.
I can communicate with the QUAD-SPI FLASH N25Q03 using both standard SPI and Quad SPI on the U1C1.

So far so good.

I have then connected the N25Q03 to U2C1 on a XMC4500F144 using the below pinout:
P4.7 - Data0
P4.6 - Data1
P4.5 - Data2
P4.4 - Data3
P4.3 - CS
P4.2 - CLK

When using the Infineon XMC pin-out tool, it indicates that this setup is possible to use for Quad-SPI.

But when looking at the view for SPI Master in the pin-out tool there is no possibillity to use this setup.
The MOSI-pins are only available at P3.11 and P3.5 (DOUT0) for SPI Master, the other P4.x pins are fine.

Why is this the case ?

Cannot the U2C1 be used for Standard SPI (MOSI/MISO/CLK/CS) ?

I have rewritten the above example to use the U2C1 and tried to send data using Standard SPI but cannot get any data on my MOSI-pin.