Yeah I had the same problem.
Two other mates used the same grip (including Piros)and we have all had the same problem.
My pad went smooth and soft as well, so after almost pulling a hammy from slipping off on a wave, I peeled it off and put a more popular brand of deckgrip with a more aggresive pattern and deeper groves and all is good now.
My advice is to stick to more well known brands
Tried sandpaper and it only killed the pad and made it worse.
Waz