Fixed Header now not working

The fixed/sticky header worked great on mobile and PC for years and is not staying fixed any more when scrolling out of range of the header as the header just disappears. How do I fix this? Below is all the custom CSS coding that I have in my simple table.

.tablepress.fixedHeader-floating {
z-index: 1000 !important;
}

.tablepress thead th,
.tablepress tbody td {
text-align: center;
}

.tablepress-id-1 .column-8 {
display: none;
}

.tablepress-id-1 colgroup {
display: none;
}

.tablepress-id-1 .row-highlight-row-empty td {
background-color: blue !important;
}

.tablepress-id-1 .row-1 td {
padding-top: 20px;
padding-bottom: 20px;
}

.tablepress-id-1 .column-1,
.tablepress-id-1 .column-2,
.tablepress-id-1 .column-3,
.tablepress-id-1 .column-4,
.tablepress-id-1 .column-5,
.tablepress-id-1 .column-6,
.tablepress-id-1 .column-7 {
width: 20px;
}

@media screen and (max-width:800px) {
.tablepress.fixedHeader-floating {
top: 0 !important;
}
}

The page I need help with: [log in to see the link]