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 This happens to me all the time while downtiering. I just split the stack and go back to what I was doing.
 By the off chance, if you are trying to downtier a stack of 95 and end up with 110 (game limit), you are most likely losing some of your resources.  I use "up to" 55, so that I don't go over that 110 limit, just in case it splits perfectly on the downtier.  I normally use 51 because I can only make stacks of 105, so that I don't end up with a stack that I need to split.
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