as a workaround enable PWM for any pin, see PR #8622

Marlin/src/HAL/HAL_LPC1768/fastio.h

 // hg42: instead use PWM bit from the #define
 
 /// check if pin is an timer
-#define _GET_TIMER(IO)        LPC1768_PIN_PWM(IO)
+#define _GET_TIMER(IO)        TRUE  // could be LPC1768_PIN_PWM(IO), but there
+// hg42: could be this:
+// #define _GET_TIMER(IO)        LPC1768_PIN_PWM(IO)
+// but this is an incomplete check (12 pins are PWMable, but only 6 can be used at the same time)
 
 /// Read a pin wrapper
 #define READ(IO)  _READ(IO)