Hi @glam,
So when you add this new calculated field to the pivot table, does it change the visual at all..is anything different occurring in those boxes or is it showing blank as it was prior to the switch?
Re-Reading the first post shared, titled ‘Replace blank/NULL values by 0’..you may need to incorporate ‘toString’.
This may be easier to assist further if you’re able to upload a copy of your analysis, with anonymized data, on to the QuickSight Arena view, that way we can test out a few different scenarios to see what may work in this case!