We have a SharePoint Classic Site which has lists that for some reason don't have the Integrate > Power BI > Visualize this list option. Some lists are ok but others don't have the option. The Lists without the option can still be connected to by Power BI via Power BI directly but the inconsistency is annoying and makes it hard to get widespread adoption for Power BI against SharePoint lists.
Looking at the difference between the lists I can't see anything that stands out and all Sites and Lists use the new modern interface. Searching the internet produces very little other than a blog from Microsoft when initially releasing the feature as a preview saying that the feature would be blocked during the preview if it was incompatible with existing lists.
Any clues as to how we can get our existing lists supported for Power BI visualization?