Masonry blog categories not displaying correctly

I have a page displaying a Masonry Blog that is showing all of the categories instead of just the one I have specified in the Category drop down list.

The page in question is: http://marconisociety.org/blog/

I am using the following quick css (not sure if there is a conflict here):

.phone-info .avia-button {
background: #90aa9c;
border: none;
border-radius: 0px!important;
margin-top: 0;
margin-bottom: -20px;
top: -9px;
}

a {
text-decoration: none !important;
}

.main_menu ul:first-child>li>a {
font-size: 14px;
}

.main-title a {
font-size: 30px !important;
}

#top .title_container .container {
padding-top: 20px !important;
padding-bottom: 0px !important;
min-height: 80px !important;
}

.home .blog-categories.minor-meta {
display: none !important;
}

.html_elegant-blog .avia-content-slider .slide-meta {
margin-top: 0px !important;
}

.html_elegant-blog .avia-content-slider .slide-entry-title {
padding: 10px !important;
}

.home .slide-entry-title {
margin-bottom: -5px !important;
}

span.blog-categories, .slide-meta {
display: none !important;
}

@media only screen and (max-width: 1100px) {
#mobile-advanced, #advanced_menu_toggle, #advanced_menu_hide { display: block; }
nav.main_menu { display: none; }}
#wrap_all {
position: relative !important;
}

span.text-sep.text-sep-comment {
display: none !important;
}