nRF52832 (SPI master function) only detects accelerometer KX224 (SPI slave) when JTAG debugger is connected; but SPI bus oscillogram is perfect

Hello together,

I have a strange problem and don't know how to proceed...

At my customer-specific electronic a Kionix KX224 is placed next to the BLE module which contains the nRF52832. When I connect my jTracePro Debugger everything works fine. But when using that electronic without the debugger, all other sensors using GPIOs or TWI work well and the results are transmitted by BLE as planned. Only the KX224 is not detected by the nRF52832, although the oscilloscope shows perfect answer from the KX224; the SPI decoding module from the oscilloscope shows the expected data.

I tried already to switch on internal Pull-Ups - no change.

Does anybody have an idea?