I reproduced your formula and definitions, with one exception, in a
blank sheet, and it worked OK. The one exception was that you have E1
in your formula whereas you should have $E$1 to make it absolute; I
used $E$1. However, this alone does not explain the situation unless
there are formulas below E1 that depend on the results in the same rows
in D. The latter would might cause a circular ref as long as you have
E1 rather than $E$1.

What cells are involved in the circ ref?