I think we have another case of where the OP has checked out....never did respond as to which rat proof feeder they had that was not working........but since there is a following of certain aspects of this thread........perhaps this might be of interest:
https://www.backyardchickens.com/threads/rat-proof-feeder-review.1180514/
Also, although Al insists on maintaining a low profile and doesn't mention it, he also has his own youtube channel where this line of products is discussed in greater depth. He has given this a lot of thought and came up with a product to help.
FWIW, there is also this thread on rats.......
https://www.backyardchickens.com/threads/rat-control-the-video-series.1337456/
Emphasis of the video series thread is in addition to presenting factual information on what you are up against with a colony of rats, is how to deal with them. Boils down to three things...
Sanitation (and that includes limiting access to feed and water......which this rat proof feeder excels at doing....at least for most standard chicken breeds)
Exclusion......how to rat proof your housing.....
and if those two fail......
Elimination
and if you want this thing to work, it is in that order.
To often folks start out with elimination by using ineffectual means like trying traps, etc. Understandable, as that is a simple thing to try. Also futile.
Bait blocks are the "nuclear option". They work, but at some degree of risk of collateral damage. Some won't accept the risk no matter what......and other's don't care a whit. They only want the rats gone. Consider it a gray scale and where you fit on that scale....from black to white.....depends entirely on you.
And that applies to any one single bait. There are about 10 different classes of baits, each with it's own risk profile and it's own gray scale. So not an easy topic to figure out.