SCLK pulses not seen when using SPI on ESP32
Try to set the pins explicitly to Output 
EDITDifferent issues with the test programs indicate that acc. to espressif the pin has to explicitly set to high which is not done by the libs begin method (as of core 1.04)

  digitalWrite(30, HIGH); // turn on pullup resistors
  digitalWrite(xxx, HIGH); // turn on pullup resistors
  pinMode(30, OUTPUT); //VSPI SLCK
  pinMode(XX, OUTPUT); //HSPI SCLK


The ESP32 docs say:


  gpio18 will output low level(because gpio18 is input mode by default).
  If you don’t want this behavior, you should configure gpio18 as output
  mode and set it to hight level before calling


As this is not the issue - the Wroom32 modules v1-3 have a problem with SPI when flashed in certain modes with 80Mhz So try flashing with 40Mhz. I check for my test program in the meantime.

So here is a working test routine:

/* SPI Test routine for Wroom32  
Connect the MISO with  the MOSI pin*/
#include&lt;SPI.h&gt;       //Library for SPI

#define SPI_SCK 18 // Serial Clock (Master Output)
#define SPI_MOSI 23 // Master Output,Slave Input
#define SPI_MISO 19 // Master Input, Slave Output
#define SPI_CS 5 // Chip Select, Slave Transmit Enable (active low, Master Output)
#define SS 5

char returnStr[40] = {'\0'};
char returnChr;

void setup () {
  Serial.begin(115200); // Set baud rate to 115200 for usart
  pinMode(SPI_CS, OUTPUT);
  pinMode(SPI_SCK, OUTPUT);
  pinMode(SPI_MOSI, OUTPUT);
  pinMode(SPI_MISO, INPUT);

  digitalWrite(SS, HIGH); // disable Slave Select
  SPI.begin (SPI_SCK, SPI_MISO, SPI_MOSI);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE0);
  SPI.setClockDivider(SPI_CLOCK_DIV8); // divide the clock by 8=2 MHz @ESP32
}

void loop () {
  char c;
  digitalWrite(SS, LOW); // enable Slave Select
  /* Send test string in a loop */
  for (const char *p = "SPI TEST! We are online over SPI\n\r" ; (c = *p); p++)  {
    returnChr = SPI.transfer (c);
    Serial.print(c);
    Serial.print(returnChr); // MOSI MISO Link sends echo back
  }
  digitalWrite(SS, HIGH); // disable Slave Select
  delay(500);
}


To measure the signals you have to trigger to the falling edge of SS/CS and set the resolution to 2µs per grid field (round about). I tested on an AIThinker module (ESP32) and everything worked with that sketch.