I've had the same experience too.
Win 7 x64, i5-2500, 8 GB, ... I think this is not a problem of my hardwares. Evernote 6.4.2.3788 for Windows. This version (and older versions maybe too) might have a bug I think.
I didn't check the 'search notes' function but I definitely have a problem searching words and lttrs on the notes having attached pdf files. When finding that in the note by doing a ctrl+F key, I cannot find the lettters and sometimes no counting of lttrs also. I already did uninstall and reinstall.
I've had the same experience too. Win 7 x64, i5-2500, 8 GB, ... I think this is not a problem of my hardwares. Evernote 6.4.2.3788 for Windows. This version (and older versions maybe too) might have a bug I think. I didn't check the 'search notes' function but I definitely have a problem searching words and lttrs on the notes having attached pdf files. When finding that in the note by doing a ctrl+F key, I cannot find the lettters and sometimes no counting of lttrs also. I already did uninstall and reinstall.