We have one site collection where new sites are not inheriting the custom master page. The site collection is set to use it, publishing features are turned on, and I can even apply the custom master page after I create the site by checking the "Reset all subsites to inherit this site master page setting". It was working before so I am not sure what changed. I even copied the custom master page down from another site collection to verify there wasn't something wrong with the custom master page itself and it still the same thing. It just defaults to the v4.master page. No of the other site collections on the farm have this problem.
Any help is appreciated.