Conditional formatting to change row color when cell value changes

I'm trying to use conditional formatting to shade "groups" of rows when the value in column A changes (so all rows with the same value are either shaded or not).  To distinguish when the key value changes, I added a new column (N) and set the value of row 1 to be =TRUE().  Then for rows 2 thru the end, I added the formula =IF(A2=A1,N1,NOT(N1)); so effectively the value of the cell in N alternates from TRUE to FALSE when the value in A changes.  This part seems to work as intended.

Then I created a conditional formatting rule where it adds a fill color to the row based on the formula =AND(LEN($A2)>0,$N2); so there has to be a value in column A and the value in column N must be TRUE.  It is shading some rows and not others, but not as expected; see photo:

The top row is A with =TRUE() in it, and the subsequent rows with the formula are correctly alternating between TRUE and FALSE when the key value in A is changing (effectively when the group changes).  But I can't figure out what the conditional formatting is doing.  I assume I've missed something but can't see it, so any thoughts are appreciated.

BTW, this is Excel for Mac v16.57.