ESP12F vs NodeMCU

[reinierdevl]

I have made a test-setup with NodeMCU and 0,96 TFT ST7735S color display. It worked just fine.
So I made my own design using a ESP8266 (ESP12F). I added all pull-ups/downs like on NodeMCU. I also added pull-ups on the SPI signals (Except CS as it is GPIO15 that needs pull-down). Setup is like this (on both NodeMCU and ESP12F)

// Display GND to NodeMCU pin GND (0V)
// Display VCC to NodeMCU 5V or 3.3V
// Display SCK to NodeMCU pin D5 (GPIO14)
// Display SDI/MOSI to NodeMCU pin D7 (GPIO13)
// Display BLK to NodeMCU pin VIN
#define TFT_CS PIN_D6 // Chip select control pin GPIO12
#define TFT_DC PIN_D8 // Data Command control pin GPIO15

#define TFT_RST -1 // Reset pin (could connect to NodeMCU RST, see next line)

On the the ESP12F it however doesn't work. The screen goes on with colored pixels, but no eclipses (using the eclipse example that came with the library)...
Anyone any idea what can be the cause. I reduced SPI frequency

#define SPI_FREQUENCY 5000000

To see if it was some interference but that didn't help. The fact that the display goes on and shows colored pixels and not stay black means it is responding, just not to the e.g. fill with black