No access to old data

Hey everyone,
I wanted to access old archive data from 2017 today, however, I could only go back to April 2018. I found that during one of the updates, Matomo seems to have changed the table prefix from piwik to matomo.
Is there any chance to integrate the old tables into the new ones? I tried moving the data, renaming the tables, merging the data, but still I cannot access data prior to that Piwik->Matomo transition.

Thank you very much in advance.
Kind Regards

Sascha Schröder