I had this issue when i set colspan
in table header. So my table was:
<thead>
<tr>
<th colspan="2">Expenses</th>
<th colspan="2">Income</th>
<th>Profit/Loss</th>
</tr>
</thead>
Then once i change it to:
<thead>
<tr>
<th>Expenses</th>
<th></th>
<th>Income</th>
<th></th>
<th>Profit/Loss</th>
</tr>
</thead>
Everything worked just fine.