Sort Changing to A-Z instead of Largest/Smallest ONLY if formulas are copied below row 406??

[J187]

Hi Everyone, I am having a strange issue. I have a table with data and formulas across from A to AG. A-I is data that is read from another sheet that I import a CSV to. J-AG consists of INDEX/MATCHs and sum formulas. To keep things clean, All my Index/Match and sum columns use "IF(A2="","",blahblahblah)" so that the cells are blank in rows after the imported data ends. Everything is fine when I run my formulas down to row 406. I set my headers to filter and have the "largest/smallest" option. The minute I copy values below row 406.... It only gives me A-Z and starts reading the empty cells as "Blanks" when I look in the filter. I have tried clearing all cells below, rebuilding the page. I have tried using a new sheet, a new import sheet. Any idea what could be causing this?

 

[J187]

Update: I have figured out that it actually limits me to whatever row would be double the rows that data exists in from my import sheet. In other words, if I have 203 rows of data in the sheet that I am copying my CSV, I can sort up to 406 rows in the main sheet. But as soon as I put formulas in 407, it goes back to A-Z. If I add a row of data to the CSV sheet so that it has 204 rows, I can go to 408 in the main.

What's going on with this??