I've known this bug for looong time and I've been waiting for an update to fix it but I gave up that hope long time ago as well. I've already developed workaround for this bug but now I'm just wondering that won't Adobe do anything to fix this annoying bug which is hard to discover.
When exporting EPUB, all the uppercase Š characters turn as non-breaking space HTML entity. This bug has existed in every InDesign CS5 version. It didn't exist in CS4 version and it doesn't exist in CS5.5 version, only in CS5 version. Just wondering, will this bug be fixed or not. My guess is that it won't be fixed.
This is not Adobe tech support. This is a forum of InDesign users. Often these forums are NOT monitored by Adobe staff.
If you've found a workaround for the bug, what you need to do is report the bug. Here is a link to that form: