For 64- bit Windows users, consider that according to the java website: "64-bit Windows operating systems (such as Windows 7, Vista or XP) come with a 32-bit Internet Explorer (IE) browser as the standard (default) for viewing web pages. These operating systems also include a 64-bit Internet Explorer browser, however using it is optional and it must be explicitly selected to view web pages. Note that because some web content may not work properly in a 64-bit browser, we recommend using the default 32-bit browser and downloading 32-bit Java." (https://java.com/en/download/faq/java_win64bit.xml).
So, as far as I understand, even though your Operation System is 64 bits, when you download Java from the website it will automatically download the 32-bit. This means that you need to have both, Java 32-bit and Java-64 bits on your machine to be able to see the map application in Hydrohub. To download the 64 bits with a 32-bit browser follow this link: https://java.com/en/download/manual.jsp and choose the option "Windows offline 64 bits".
This is how I solved the problem with not being able to see maps in Hydrohub, hope it helps other 64-bit Windows users.