There is something strange in newthread.php, and that may cause it. But I thought we already tried for line 71:
But this should work, else I read the code wrong. Please try it.
Dinner time!!
.
Almost 18:00h here, after 19:00h I'll be gone for this evening. Hope this last one works, at the end I send you an updated version because I see it also needs some optimization.
$post_link = $mybb->settings['bburl']."/thread-".$tid.".html";
But this should work, else I read the code wrong. Please try it.
Dinner time!!

Almost 18:00h here, after 19:00h I'll be gone for this evening. Hope this last one works, at the end I send you an updated version because I see it also needs some optimization.
Regards, Ad Bakker (NL)