No problem signing in on each of the two Apps but as someone else reported, choosing "Full Site" from the SPG App takes you to your Marriott account. The "Combine Accounts" functionality is still greyed out as "Coming Soon". The full site is still headlined "New loyalty benefits are on the way! Until then you may experience a temporary disruption etc. etc." Working in IT and having project managed a few upgrades in my time I'd suggest they didn't spend enough time on testing - probably let the preannounced deadline force them to cut corners and now they're paying for it