Trouble in connecting SSD1306 display to defalut I2C pins of ESP32 Devkit C v4!?

[cemox]

Thanks for this great library.

I cannot figure out why my SSD1306 (noname 128x64 oled) display works like a charm with:
U8G2_SSD1306_128X64_NONAME_F_HW_I2C oled(U8G2_R0, /* reset=*/U8X8_PIN_NONE, /* clock=*/22, /* data=*/23);

but does NOT when the default I2C pins (21, 22) are selected with:
U8G2_SSD1306_128X64_NONAME_F_HW_I2C oled(U8G2_R0, /* reset=*/U8X8_PIN_NONE, /* clock=*/SCL, /* data=*/SDA);

Actually, in the latter configuration (i.e. default I2C pins), display works occasionally, it is not stable.

No doubt, SCL and SDL names correspond to correct pin numbers, I checked it.

All the external pull-ups etc. are ok. Also tried with different boards and different displays. Any ideas?

Setup: SSD1306 128x64 Display, ESP32 DevkitC V4 Board, PlatformIo, Arduino framework, all libraries and the platform are the latest versions.