A bug in Microsoft Word has had me baffled for several hours and at various times in the past. I thought it was me. But it’s not –it’s Word, and it’s a bug that’s been around since at least 2006. Microsoft have never bothered to fix it (I use Word 2010 and 2013 and it’s evident in both those versions).
When you do a Wildcard find/replace in Word AND you have track changes turned on, the replace action transposes/reverses the items you want to replace!
For example, I have numeric values followed by their units of measure (e.g. 90 km) and I want to replace the normal space with a non-breaking space. To do this, I do a wildcard Find for ([0-9])( )(km) (i.e. any numeral followed by a space followed by km), and a Replace with \1^s\3 (i.e. replace the first part with itself, delete the normal space and replace it with a non-breaking space [the ^s bit], and replace the third part with itself).
If I have track changes on when I do the Replace, I get this: 5km<non-breaking space>, instead of 5<non-breaking space>km.
How to avoid it
Turn off track changes BEFORE you do the wildcard find/replace.
See these sites for information on how long this bug has been around, and other examples of it:
[Links last checked February 2015]