If the sync stops immediately, during the sync of the first calendar, then turn "Settings", "Display and Use", "General", "Advanced", "Upload before download" off. Afterward restart CalenGoo using the task manager or reboot your iPhone/iPad to stop the running sync. Then it should sync correctly again.

It will be fixed with the next update probably in about a week, but when "Upload before download" is turned off, the sync should already work correctly again.

The "Upload before download" option usually has only an effect if you saved events while being offline. Then they will be uploaded with the next sync before other changes will be downloaded. However by default changes are uploaded immediately after saving an event so normally there are no changes to upload during a sync and thus "Upload before download" makes no difference.