Problem with Wire.h, between MKR 1010 Wifi and Uno - ,,multimaster"

Dear Arduino Community,

I have a problem with the wire library of Arduino.

I tried to implement a two-way communication without the request function,
because I had a problem with the interrupt in requestFrom.

But this does not work. It seems that the messages never arrives, or to be more precise:
receiveI2C was never called, on both sides.

MKR 1010 program:

#include <Wire.h>
 
#define I2C_ADDRESS_OTHER 0x1
#define I2C_ADDRESS_ME 0x2
 
void setup() {
 Serial.begin(9600);
 Serial.println("MKR");
 Wire.begin(I2C_ADDRESS_ME);
 Wire.onReceive(receiveI2C);
}
 
void loop() {
 delay(5000);
 Serial.println("MKR");
 Wire.beginTransmission(I2C_ADDRESS_OTHER);
 Wire.write("hello world from 0x2 to 0x1");
 Wire.endTransmission();
}
 
void receiveI2C(int howMany) {
 while (Wire.available() > 0) {
  char c = Wire.read();
  Serial.print(c);
 }
 Serial.println();
}

Uno program:

#include <Wire.h>
 
#define I2C_ADDRESS_OTHER 0x2
#define I2C_ADDRESS_ME 0x1
 
void setup() {
 Serial.begin(9600);
 Serial.println("Uno");
 Wire.begin(I2C_ADDRESS_ME);
 Wire.onReceive(receiveI2C);
}
 
void loop() {
 delay(5000);
 Wire.beginTransmission(I2C_ADDRESS_OTHER);
 Wire.write("hello world from 0x1 to 0x2");
 Wire.endTransmission();
}
 
void receiveI2C(int howMany) {
 while (Wire.available() > 0) {
  char c = Wire.read();
  Serial.print(c);
 }
 Serial.println();
}

But the samples on arduino.cc works perfectly, but they use the request function and I don't want to use them!

If anyone asks, SDA and SCL are properly connected.

receiveI2C is called in interrupt context, so never call any method in that function that depends on interrupts (as Serial.print()).

I2C multimaster doesn't work reliably. Always define one device as master, the other as slave!

But the samples on arduino.cc works perfectly, but they use the request function and I don't want to use them!

Why? The Wire.onRequest() as well as the Wire.onReceive() function is called in interrupt context so you have to take care for that in both.