Thanks for accepting! Doing a startup, I can see how these things are easy to miss/forget. In fact, I ran into just the same issue with Medium today, where posts that were added to my collection are nowhere to be found, except for email. @Medium got back and told me they haven't developed the interface yet. Fair point, I almost expect that from a company that's growing and constantly iterating. But given the size and maturity of LIN, one would hope for a better experience. Glad you found the link after all :)

Mailbox icon (4th icon from top right). Either check the drop down list or if you click through, look for the invitations tab.

Top right corner of the web site, there's a few icons. Click on the envelope looking one.