Same issue here... (iOS v10.14 and Mac v10.18.3 app)
I tried using the 'Copy Internal Link' feature on my iPad and iPhone, and the links do resolve to the local link within the Evernote iOS app. ✅
However, when I open that same note (with the same "Internal links") in my Evernote desktop app (Mac), it opens the links in the web browser instead of within the Evernote desktop app. 😮
Upon review of the links, the internal links created on the iOS device start with 'https:', but creating an internal link in the Evernote Desktop app using the 'Copy App Link' option, the link starts with 'evernote:'.
So, it looks like there is a difference in how Evernote mobile (iOS) internal links are created and resolved versus the Evernote Desktop app. 🤔
This issue may have been discussed in a post I have not seen yet, but is Evernote aware of this (I am assuming they are)? If so, is this issue on the 'to fix' list?