We are using the CYBLE-212006-001 in a project with SPI, we have it set for three slaves, on SS0,SS1,SS2.
I must have missed it in the documentation, but if you want three slaves, number three, which should be SS2, is actually SS3, so in the function call SPI_SpiSetActiveSlaveSelect(2); if you specify a 2 as shown no SS if fired. The PIN names, etc are refer to SS2, but regardless it will never work.
If you specify a 3, SPI_SpiSetActiveSlaveSelect(3) it works fine; now it makes sense as that is the SS brought out in this module by carefully noticing that there was no SS2 in the pin assignments.
Going back I found no reference to this in the documentation, and the SPI widget did not issue me a warning, this cost us two days to figure out, do you plan to better document this "feature".