According to information found on the Microsoft Social website (aka forum), the problem with flipping and rotating is directly related to the document where the WMF file is embedded in. You will have to change the hosting word file. Additionally, make sure to implement every record for all the files to look the same for all the opened files. It has been reported that this issue happens with EMF files as well, and the files are working normally in Paint (Windows GDI example).
