Workflows Not triggering after migration from Dynamics 2013 to 365 on premise. Each rule part must be a name-value pair separated by '='

After migrating from dynamics 2013 to 365 none of my async workflows are working. I get the following error but have not found a solution to my problem

An unexpected error ocurred while executing an asyncoperation of type 1 for organization bfa0a374-d7f2-e311-80c7-00155d500103. Exception: Microsoft.Crm.CrmInvalidRecurrenceRuleException: Each rule part must be a name-value pair separated by '='. Actual number of fragments: 1

at Microsoft.Crm.RecurrencePatternFactory.Create(String iCalRecurrence, DateTime patternStart, TimeZone timeZone, TimeSpan duration)

at Microsoft.Crm.ObjectModel.AsyncOperationControlService.NextOccurrence(String pattern, DateTime recurrenceStartTime)

at Microsoft.Crm.Asynchronous.AsyncOperationQueueManagerBase.UpdateEventState(AsyncEvent asyncEvent, AsyncHandlerResult result)

at Microsoft.Crm.Asynchronous.AsyncOperationExecutionManager.EndAsynchronousEventProcessing(AsyncHandlerResult result)

at Microsoft.Crm.Asynchronous.PoolHandler.ProcessAsyncEvent(IAsyncEventExecutionManager asyncEventExecutionManager)

at Microsoft.Crm.Asynchronous.Operations.AsyncEventOperation.<.ctor>b__2(IServiceOperation operation)

at Microsoft.Crm.OperationBehaviors.FaultToleranceBehavior.Execute(ServiceOperationAction operation, IServiceOperation operationParameter)

The Asynchronous service is running on a backend server and the following message is displayed in the event logs and CRM debug logs. Has anyone came across this issue before ?

Thanks in advance G