'Select Columns' config screen is blank for large worksheets

[Proulx06]

I was looking around here to see if there is a limitation on the extension, but it appears there is not (we're on 2021.1). However, when trying to export large worksheets (50+ columns, 50,000 rows, for example) the 'Select Columns' screen in the config is blank. I assumed it was just chugging, but it never shows up. Tried this on multiple dashboards but the same concept (large worksheets). The extension works well with smaller, more reasonable worksheets.