Station callsign field must be returned by mysql to be shown.

application/views/view_log/partial/log.php

@@ -63,7 +63,7 @@
 			<?php } ?>
 
 			<?php if($this->config->item('callsign_tags') == true) { ?>
-				<?php if($row->station_callsign	 != null) { ?>
+				<?php if(isset($row->station_callsign)) { ?>
 				<td>
 					<span class="badge badge-light"><?php echo $row->station_callsign; ?></span>
 				</td>