In my time playing Dead Cells, I feel like there have been many times when, in the middle of some heavy combat, I was sure I pressed the shield or roll button with the correct timing to parry or dodge an attack, but my character just didn't do the action, or did the action much later than I pressed the button, causing me to get hit. I suspect that one reason for this might be that I was doing some other action (probably attacking) and I couldn't block or dodge until the animation for that action was finished. However, when I test with no enemies around, it seems that most of the time I can cancel an attack animation in order to roll or block immediately. So, I just don't feel like I have a good understanding of when I can and can't block. What are the rules for which actions can be cancelled (roll, block, attack, etc.) in order to perform some other action immediately? Is there a strategy that will ensure that I'm always ready to block/roll at any time, or does attacking always introduce a window of time where I can't defend?
I know the developers introduced a lot of hidden helper mechanics to make the game more fluid and accessible. So it could be the reason why you cannot reproduce the same animation cancel when close to ennemies.
Other than that my personal feeling is that your actions queue to a certain extend. So maybe trying to pace yourself and avoid inputting multiple attacks would allow to dash when you need to.