Great news! I was able to locate the issue.
From what I can tell, this is an issue on Instagram’s end. For some reason, the limit isn’t always respected for tag queries. I’ve found posts of other people reporting the same issue, so it seems pretty well documented as a bug.
The good news is that I’ve created a little fix for it that should suffice for the time being. If you’re comfortable with doing a simple edit to the plugin yourself, you can edit the file at includes->simple-instagram-shortcodes.php. Paste the following code at line 22:
if(count($feed->data) > $limit){
$total = count($feed->data);
$diff = $total - $limit;
$start = $total - $diff;
for($i=$start; $i <= $total; $i++){
unset($feed->data[$i]);
}
}
It’ll go after the line if(($feed) && count($feed->data) > 0){
and before the line $return = '<div class="si_feed">';
Otherwise I’ll be pushing a new version with this fix included here shortly, so you can update instead.
Thanks for your help in getting this nailed down!
mr_speer