That is not a hook but a function called by the save procedure.
Inside you’ll find the filter you’re using.
My advise is to try a debugger (I use Xdebug) to get more insight into the call order.
- Set a breakpoint after the line where the filter is applied in
post.php->sanitze_post_field and
- Set a breakpoint in your filter handler.
If breakpoint 1 is hit but 2 wasn’t, then you know your handler isn’t hooked correctly.
I hope this helps you a step further in you investigation.
As your issue is not related to this plugin, I would kindly ask you, to ask further community assistance in the ‘Developing with WordPress Forum’.
IMHO the moderator there shouldn’t have closed your topic there.
Success!
Kind regards