Build model upon saving endpoint
Change behaviour when saving endpoint.
When saving a new endpoint, e.g. to a new lambda version a green pop-up appears. This most likely represents success for most users. But the text says, that the skill has to be build before the change becomes effective. This might easily be forgotten. For example, before I submit a skill for certification I always publish a new version of my lambda endpoint. If I forget to build the skill after adding that endpoint to the skill it might point to $LATEST. That means changes to the lambda would affect the skill in certification or even the live skill.
At least that's what I must assume.
Please build the skill automatically when changing the endpoint or at least a a pop-up with another color than green and a button that I can click to build the skill immediately.

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Eric Olson commented
Changing one or more of your endpoints requires a rebuild of the skill's model. Unlike every other screen on the Build tab of the developer console, however, for some reason the "build model" button doesn't appear on the endpoint screen. Only the "save model" button is available. The result is that users are likely to save their model but not rebuild (even though the save notification reminds you that you need to build), meaning their changes won't be reflected the next time they test.
This ticket is related to, but does not duplicate: https://alexa.uservoice.com/forums/906892-alexa-skills-developer-voice-and-vote/suggestions/33976015-build-model-upon-saving-endpoint