INDEX SMALL array formula issue

Hi. I'm trying to use the formula below to pull the values from column B according to the values in column A. I copied this from another website which I can't find any more unfortunately.

=INDEX($B$2:$B$50, SMALL(IF($A$2:$A$50=1, ROW($A$2:$A$50)-MIN(ROW($A$2:$A$50))+1, ""), ROW(A1)))

This is then made into an array formula to display the values from column B that have a value of "1" in column A in a separate column. I have values from 1-10 in column A which I wish to sort into separate columns, one column for value 1, one column for value 2, and so on, and will have additional formulas for that further across the sheet.

The problem I have is that this formula will only display the first matching value in the data. As I understand it the ROW(A1) function at the end is there to increment the data, increasing by 1 with each row it is copied down.

However, when I try and make the array formula (select the range, paste the formula into the bar, and then Ctrl-Shift-Enter) the A1 reference doesn't increment, meaning that I only ever get the first value. Could anyone advise what I'm doing wrong?