We had a Salesforce sandbox integrated with Marketing Cloud and refreshed the sandbox without previously disconnecting the Marketing Cloud Connector. Now we see this error message: InvalidParameterException: Whoops! Marketing Cloud Connect does not have access to the selected object. Contact your administrator to enable objects for Marketing Cloud Connect triggered sends. Is there anything we can do now to solve this issue? Or do we have to contact the support?
You can have a look at: https://help.salesforce.com/articleView?id=000268883&language=en_US&type=1 regarding the remote site setting named "MetadataAPI".
Also have a look at: Will Instance Refresh in salesforce effect the marketing cloud connector integration