As suggested above… please create your own topic with your specific problem… as mine was a very subjective question (NOT really a Blynk problem), way back in my early days of Blynk.
Meanwhile, the short story is that since Blynk needs constant processing in the background to do it’s thing, and since I was using a rather slow MCU (16MHz Arduino) at the time, I was simply doing too-much-too-fast and something was getting lost in the slider input (the widget was probably set to constantly update as moved, instead of update after release… too long ago, can’t remember).