Hi Havala, would you mind sending a screenshot with an example of the issue you are experiencing?
I am not aware of the exact limit of data points for the Bar Chart visualization, but if you do reach it the visualization will simply fail with “Too many data points to display”.
I ran a few tests, and noticed that if you build a bar chart and View by an Attribute with a lot of entries, the Legend will adjust the values displayed according to the resolution of the screen. So if you zoom out you should see more values appear. Still, the chart itself will display all bars, which you can check by running the mouse over them. I’d say that’s the truncation you noticed.
Based on those tests and your description of the issue, I would recommend utilizing a different visualization. Another option is to filter it so that you have fewer values being displayed on the chart, or build the chart viewed by a less detailed attribute (then you can create a Drill-down so that users can go to a deeper level of detail by interacting with the insight).