I have implemented workaround while waiting Shopify to response about this.
Add / as Homepage/Dashboard will restore the 1st nav menu. Before adding this, our Point Programs nav menu disappeared!
We’re having the same issue with our app. It seems there is a paragraph in the AppBridge docs that explains this behavior. I don’t remember seeing this before though: ui-nav-menu
The first element is required and used to configure the home route of the app. It is not rendered as a link. It needs to have rel="home" set along with the href set to the root path.
This definitely seems new and broke my app navigation. Adding an another link home link works. I wish we could back to app-bridge being versioned. Breaking changes like these are becoming way too common recently.
Also seeing this issue. We’re working on handling it by adding the defined home link, but it would be great to know if this was an unintentional change that will be changed again or if this is the correct handling moving forward. Either way, unannounced breaking changed like this in App Bridge are getting pretty tiresome.