I can confirm the bug. Custom board with F746 chip, 4-bit SD card, FatFS(!). Version 1.10.1 of CubeIDE  generated this code: static void MX_SDMMC1_SD_Init(void) { /* USER CODE BEGIN SDMMC1_Init 0 */ /* USER CODE END SDMMC1_Init 0 */ /* USER CODE BEG...

I thought that Unicode::snprintf(letter_buffers[i], 2, "%s", "W");is good enough as initialization. At least it worked for me.

See this discussion: https://community.st.com/s/question/0D53W00000ttGs7SAE/creating-textarea-programmatically-with-wildcard-and-buffer

class FastEditScreenView: public FastEditScreenViewBase { ... private: touchgfx::MoveAnimator<touchgfx::TextAreaWithOneWildcard> letter_boxes[LETTER_COUNT]; touchgfx::Unicode::UnicodeChar letter_buffers[LETTER_COUNT][LETT...