I just updated the Moodle Desktop app to version 3.5 (through the Mac app store; running MacOS 10.13.3). When I launched it, it asked me to enter the site (I guess it didn't remember the site that I previous version had been configured with, which I thought was weird). After entering the site URL, I get our Shibboleth sign-in page, as expected. But it won't accept my credentials. I get a "The username you entered cannot be identified" error. I know I'm entering my credentials in correctly. And they work when logging into our Moodle site from a web browser.
I tried deleting the app and reinstalling. Didn't help. It won't accept my credentials (which are correct).
My credentials work fine on the iOS version of the Moodle Mobile app (v. 3.5).
Any ideas as to what might be going on?