Hi, this sounds like an issue for tech support...
In 7.0.7, Tableau is saving the Excel file as unicode. I've looked at both 7.0.7 exports as well as 7.0.6 and 7.0.8 exports within a binary editor. The files are significantly different. We were on 7.0.9 but had to downgrade due to nightly extract bugs. However, 7.0.6 has too many bugs and 7.0.7 has the Excel export bug. We're stuck with 7.0.7.