I have just upgraded KMyMoney from 4.6.1 to 4.6.2. Prior to this encryption was working fine (Gpg4Win installed).Now KMyMoney will not open encrypted files, and the "Use Gpg encryption" option is greyed out in Settings.Reinstalled Gpg4Win and restarted, but to no avail.
Looks some package is missing that is required by KMyMoney to use GPG4Win. I am not familiar with the MS-Windows environment to provide more details. Sorry.
In 4.6.4 encryption works but keep in mind these comments https://forum.kde.org/viewtopic.php?f=69&t=119070&sid=58301f69280786bf152321f9c18db0d9.