Trying to figure out if I use CountIF, CountIFs with multiple criteria and logic.

PeterBartholomew1 , IMHO the main question here is what we consider as empty cell. That could be the blank cells (no content at all) only, or blank cells and cells with empty string ("", which we usually use to imitate blank cells). If do small test we will see the difference

Here two yellow cells are with empty string and one cell is blank. Total 6 cells, 2 empty plus 1 blank.

COUNTA() doesn't consider cells with empty strings as blank and count them, same do COUNTIFS(). Just in case, COUNTBLANK() in opposite counts both blank and empty ans blanks. SUMPRODUCT() does correct calculations excluding all cells with empty strings and blank ones. Variant with LEN() is more straightforward and gives less reasons for misinterpretations.

As for @ that's not wildcard, only the character which is more close to the beginning of ASCII table compare to other characters. However, # is even earlier plus any number is always less than any text, thus formula counts only the cell with a1.

Back to initial question I'd use SUMPRODUCT like

=SUMPRODUCT((B2:B206="SU036")*(LEN(E2:E206)>0))