Galaxy S6 not restoring S Planner via Smart Switch Backup

[AC Question]

I recently backed up my Galaxy S6 via Smart Switch and then carried out a factory restore due to some other issues.

I have restored my phone using smart switch and everything has worked ok except for S Planner calendar.

I get a message saying
Unable to Sync Calendar.
To use Sync calendar, tap SETTINGS, go to App info > Permissions, then allow the following permissions: Calendar.

Although I have to go through a different set of directions to get to the permissions it appears that they are allowed but the calendar still wont restore from the back up.

Help as there is a lot of info in my calendar that I need.

Thanks in advance.