The Linchpin Mobile app on a user's mobile device cannot connect to a Confluence instance via direct connection (= not via Linchpin Mobile Gateway). Basic authentication is disabled for target Confluence instance (requires Confluence 7.14 or above).
With Confluence 7.14, Atlassian introduced a setting that allows disabling basic authentication for user login. Since our Linchpin Mobile app relies on basic authentication when connecting directly to a Confluence instance (not using Linchpin Mobile Gateway), disabling basic authentication results in mobile users not being able to log in any more.
At this point, you have multiple options to proceed:
Enable basic authentication for your Confluence instance in order to make mobile logins work again.