I will ask my question via linking some other question asked by someone. S/he got his/her answer on how to solve, but I am more interested on WHY? Thanks in advance.
Link to the question: STM32 ADC conversion using HAL
Almost the same issue ( eoc selection thing ) confused me for a considerable time too. I still don't know why? Its explanation just says that set the EOC flag at the end of each channel conversion, so yes this also should work. Convert channel 1 (only one channel, nothing interesting, one measurement only) for example and then just set the EOC flag and reset the measurement cycle. What is the reason why this does not work with single conv eoc choice?
