Hello @Indy96
Thanks for bringing this to our attention, for this type of issues maybe the first step will be to confirm if the Workspace and report still exists, if so, do you have access to manipulate them with the same user that you are creating this flow?
If the answer it's yes, then my recommendation will be to open a support request as additional information and traces will be required, specially since the error message is nor explaining much of the underlining issue to suggest additional ideas.
I hope this at least can point you in the right direction.
Thanks.