I often have a request to display custom data in a search hover panel in SharePoint 2013. No big deal…pop open the IDE of your choice (BTW, if you have a favorite IDE other than VS or WebStorm, leave a comment) and create a new display template, add your managed property mapping using the managed property field name, associate the new hover panel with the search result, go get a beer. At least that’s what I normally do. J
Except it doesn’t work and you bang your head against the desk trying to figure out why. It could be because you forgot to also add the managed property mapping to the “parent” display template that calls your new hover panel display template. This is required, and often missed. I can’t count how many times I’ve forgotten that step so feel in good company if you’re reading this and in that situation.
Now go get a beer.