We have this major issue for 2 clients:
Piwik connector version: 1.0.8
Visualizing data that involves Google Ads dimensions and metrics (like Campaign ID and Cost) triggers this error, but only when a filter is applied.
The Connector does not return ANY data for the dimension Campaign ID (Google Ads) for times when we clearly see data in Piwik Pro.
In Looker Studio (link: https://lookerstudio.google.com/u/0/reporting/e69d1ea4-875a-4a42-a39b-fb079ca794aa/page/p_gc4fnb9d9c/edit), getting the same data returns error ID: 0afbc5a8 for the Campaign ID table, but the Campaign Name table works.
Moreover, when adding ANY filter to the Looker Studio dashboard and clicking any value in that filter, no Google Ads data from Piwik Pro shows anymore, not even Campaign Name.
Note: I have also created a ticket for this, but I am sure it is important for others as well. And maybe others have an idea on how to solve this. I assume though that it is a bug.