Can you please check if:
1. your confirmation includes to parameters &request=xyz&confirmation_code=xyz
If not, you could try to manually copy the link and see if that works?
2. in your database there is a table named ‘gdpr_requests’ present.
If not, you could try to re-install the plugin.
If neither of the above fix your issue, please let us know.
One more question.
In GDPR Data Report and Right to be Forgotten you do not have information about your posts if you have some kind of front end submuting plugin. You do not have plane insert posts to report/delete data and bbPress plugin?