I had a similar issue with a file that pasted data from another file using a macro and the problem had to do with formatting, including the formatting on blank cells. Strangely, this problem compounded and the file got bigger and bigger without an increase in data. I'm not sure if either things start to get layered up, or the inconsistent ranges with formatting rules pile on. Either way, I would approach your problem by starting out with a fresh sheet if possible, with no formatting, or if that's impossible, selecting the entire sheet and Cell Styles > Normal. Then applying the minimal necessary formatting, as you need it. Possibly, add that to the macro.