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Sorry, I believe your issue is invalid.
Step 1: Put Frost Walker on boots.
Step 2: Put it on an armor stand.
Step 3: Find a river or any body of water.
Step 4: Step in between the block and water then do
"/tp @e[type=armor_stand]"
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Thank you for your reply. I tested this and /tp command seems to make it work. I think what I failed to realize earlier was that armor stand needs to be moving for it to create ice and somehow when moved simply one block with piston isn't enough. I'm not sure if this is intended or not:
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It seems to have same results without optifine on:
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