SPI Slave using FSP on RA6

Has anyone used the RA6 (or anything in the RA family) as an SPI slave using the FSP?

I'm currently working with the latest FSP on the EK-RA6M1 eval board. Things work OK using the SPI as a slave if it is in clock synchronous mode, but I can't use that since I need to have communications use the chip select.  If I put the SPI module in SPI mode as a slave I can't get any data coming in.

So I'm wondering if anyone has used an RA device as a slave with the FSP, or if it is one of those cases where you can set it up as a slave, but it isn't really supported in the generated code and has to be done by hand?