Strange bug in Stacked Column - data not visible unless filter explicitly selected

[SevsBo]

I've recently migrated some data sources, with like-for-like data (columns, data types etc), but I am now encountering an interesting data glitch in one of the visuals.

I have already created a new visual on a new blank page with no filters on it, to remove any hidden filters, and have double-checked that the data in question exists in the model.

Here is the data that is visibly missing compared to the same version on old data source:

September 2024 is only showing 245 results, and I know we're missing about 1280 compared to old data. This data exists in the model, we can see it, but is not being shown here, despite no filters being applied - this is on a completely blank page and a brand new visual made especially for this test.

But here's the interesting part.

If we add the same column that's used as the Legend on this visual to Filters on this visual, and explicitly select the value we are missing, we get this:

Now we can see the correct result for this - other columns do not appear to suffer the same issue.

If I compare this to another item (November 2024; 700 is the number we're looking for)

This is correct, we see the same in the data.

And if we explicitly select this one type by again using the column that populates the Legend, as a visual filter, we get this:

It works perfectly fine!

Any idea what could cause a data issue with one specific type of activity, as outlined above?

[SevsBo · Accepted solution]

I resolved the question - we have too many elements in the field that populated the Legend, so only a few are actually shown. Once we remove the Legend, or replace it with some more restricted field, we get all the data back.