What are you using to cut it? The trick I found with the pull cutters is to set it then slap it with your hand to make the cut in one go. Also, once the blade is a bit dull, it’s over and you’ll need a new one.
FYI French and never heard of a pill cutter. Used my fingers for the last 30 years and I would estimate the failure rate at well below 1%. It is just that the dent on this one is u shaped, while nearly all other are v shaped, making the snap easy easy. Also pill cutter seriously? Heard of knifes?
Pill cutters are situationally easier for the elderly to use. They're portable, don't require a cutting surface, and generally have guards along the blade making it safer than a knife.
What works for me is snapping it while my fingernail is in the groove. Gives a clean break down the center like every time.
The dent signifies that there's an even distribution of active ingredients across the entire pill. It's a break line but it's purpose isn't for hand-snapping
Take a coin with a head on it. Put the grove over the raised face with groove side up. Press both ends of the pill down with thumbs. It breaks the pill along the groove.