STM32 SPI Clock will not idle high
I was running into a similar issue and after days of research and debugging, I noticed a trend that everyone who was having this issue configured their SPI as RX only.  When I changed my SPI to TX RX mode the issue was magically solved.  I'm not sure what could cause this, but it seems like a bug on ST's end, either as part of the HAL library, or as part of the device itself.  Either way, now I just have an unused MOSI pin configured, but the SCK idle problem has been solved.  Hope this helps save someone some time and headache!