Issue sorting/filtering on Transactions tab on Foundation Template

I was trying to filter my transactions for a specific category and then sort by amount on the foundation template to see my largest expenses within that category. I have around 6000 rows in my transactions tab. When I filter or sort by the category, it appears that only the first half of the rows are included in the filter. Past that, I see a green line signifying the end of the portion of the sheet that is being correctly filtered, and underneath the line I see all the remaining transactions that are not filtered by the category I selected.

The same issue happens with sorting - if I sort by amount (without any filtering), only the first 2800 rows or so are sorted correctly, and the rest of the sheet just shows all the remaining transactions without any sorting.

Is this an issue with google sheets, the template, or am I doing something incorrectly?

Welcome! Select the entire sheet (click upper-left box, left of A, above 1) and toggle the data filter off/on (Data > Remove filter; Data > Create filter). This will reset the filter to use the entire sheet.