There are known issues with Planning Center Online and Macs at the moment. It seems that Planning Center Online has changed the format of their cookies that we retrieve; this is leading to issues with importing presentations from PCO as well as linking PCO accounts. We are actively working on a solution and plan on releasing a fix as soon as possible.
In the mean time, a workaround is to do all PCO-related tasks on Windows. Windows has not been affected by this issue, so importing presentations and linking PCO accounts on Windows machines will work.
