U8glib funny problem I have strange problem with u8glib library. I have code:

void void_Menu_draw_func_men()
{
  if ( menu_redraw_required != 0 ) {
   u8g.firstPage();
    do  {
     Menu_draw_func_men();
   } while( u8g.nextPage() );
   menu_redraw_required = 0;
  }
}

void Menu_draw_func_men()
{

  u8g.setFont(u8g_font_6x13);
  u8g.drawStr(30, 0, "Funkcje");
  u8g.drawStr(15, 15, "Zerowanie modulu");
  u8g.drawStr(15, 30, "Modul na max");
  if(menu_pos == 0){u8g.setCursorFont(u8g_font_cursor); u8g.setCursorStyle(144); u8g.enableCursor(); u8g.setCursorPos(10,20);}
  if(menu_pos == 1){u8g.setCursorFont(u8g_font_cursor); u8g.setCursorStyle(144); u8g.enableCursor(); u8g.setCursorPos(10,35);}
  u8g.setPrintPos(5, 50); u8g.print("R:  "); u8g.print(pot_R , 2); u8g.print("   L:  "); u8g.print(pot_L , 2);

  Serial.println("func md");//just for check...

}


And oled display shows only cursor and I can move that cursor as I change menu_pos value. But no letters or values are printed on screen. Only cursor...

If I copy and paste only code from void Menu_draw_func_men(); to other part of my program:

void void_Menu_draw_test_man()
{
  if ( menu_redraw_required != 0 ) {
   u8g.firstPage();
    do  {
     Menu_draw_test_man();
   } while( u8g.nextPage() );
   menu_redraw_required = 0;
  }
}
void Menu_draw_test_man()
{

  u8g.setFont(u8g_font_6x13);   //replace this dwo lines
  u8g.drawStr(0, 0, "wykonywanie tefsdfs man...");

}


Everything works perfect... I was trying to change void name, and I don't know where is problem...
This is on Arduino Uno; I have 66% used of program memory, and 60% used of dynamic memory.
Maybe you have some idea?...
Your void_Menu_draw_test_man() function checks menu_redraw_required

Does your other part of the program update that variable? Do you call void_Menu_draw_test_man() from the loop() function?

It may help if you show the complete code, rather than small segments, since there are variables, such as menu_redraw_required, which are not changed anywhere in what is visible.

Note also that u8glib is no longer updated in favor of u8g2