Now it is still in 40-50% rough chip shot, 10 yard shot, still three yards to the green surface. Hit same shot, perfect, same power, same everything, and this shot went the resulted 8 yards with three yard roll and went into the cup. Explain why three shots in a row with the same club, same power, and same accuracy ends up with three different results.
1. You used the wrong shot type from the initial lie. By my reckoning, you originally lied 12 yds from pin, of which 5 - 6 yds was rough or fringe - 40% - 50% of the total distance. Depending on club and ball characteristics, one can expect that just ~ 25% - 35% of a chip shot is carry, and the rest is roll ... from a perfect lie or short rough. If you'd considered the pitch or flop shot types (depending on terrain in the landing region on the green, I pitch to uphill or level region - or flop to downhill or down-wind region). The pitch is 50% - 75% carry from good lies, somewhat less - depending on applied spin - from 40/50 rough. The flop is almost all carry from good lies, but as depth of rough increases there is a considerable distance penalty - again variable depending on club, ball and spin applied.
2. When WGT says you're in 40/50 rough, it is somewhere in that range. Likely the 50% end for your initial lie because it landed with more force than the subsequent chili-dips. Part of good play is taking into account the variables you face with each shot: depth in rough is approximate, strength and direction of wind is variable (+/- 10 or 15 degrees for direction and maybe +/- 30% for strength!).
Next time, using chip shot and reverse view, take the aiming arrowhead and drag it away from pin and towards your lie to the edge of green on the line of your intended shot; now ask yourself: Is the distance from my lie to the edge of the green > 20% of the total distance to the pin? If that answer is yes, do not attempt the chip shot type!