Text value is repeating

[naledi_h]

I have a table with repeating values that has worked fine so far as a slicer but has just started to show every value individually even though they are the same. 

The field that is no longer working is "Group Question Label". I am comparing it to the field "Question label (user friendly). As you can see they both repeat in the data source. 

But when shown in a table (no other fields used), Group Question Label repeats for each value when it shouldn't (and didn't previously)  

I checked to see if there were slight differences between the values, perhaps some spaces, but the filter only lists the values once, so they should be the same.

What might be happening here?

[naledi_h]

Thanks for the quick response, it was the sorting. I had created a sort field that had been affected by a recent change in Power Query so it wasn't unique anymore. The duplication resolved when I removed the sort and I got the warning about non-unique numbers when I tested adding it again. Fixing the calculation to create the sort allowed me to resolve the problem.  

[AllisonKennedy · Accepted solution]

@naledi_h  If you use 'Sort by Column' or if you mark the column as a Key in the Model view properties then it will show each duplicate value multiple times. Is there a chance that you did either of those things recently?