I have, through a great deal of trial and error, deduced that some
things appear to suppress the normal execution of the
Workbook_SheetChange and Worksheet_Change events. For example, if a
cell uses Excel's Validation feature, changes to that cell will not
trigger execution of the Change events. Also, it appears that if a
cell has a Comment that the Change events are likewise suppressed. The
reasoning behind this design escapes me, but I have resigned myself to
those inconsistencies.

My problem is that there is apparently some other property of a cell
that will also suppress the execution of the Change events, but I have
been unable to isolate what it is. I have two cells, one is R273C2 and
the other is R274C2. Whenever I type a new value into the former, the
Change events fire as expected. But when I type a new value into the
latter, the Change events are not executed at all. If I hit the Delete
key in either cell, the Change events are executed.

Neither cell uses Validation or Comments. Indeed, I have taken great
pains to insure that NO cells on the entire Worksheet use either
Validation or Comments.

I have copied the formats of R273C2 to R274C2, but no change was
evident. Then I copied the entire cell R273C2 to R274C2, but still no
change.

I began to think that it had something to do with Row 274, so I
checked cell R274C9, but it worked as expected and triggered the
Change events.

The cells I have referenced are actual cells. However, I also have the
same problem with other cells. I'm sure that there must be some other
"exception" other than Validation and Comments, but I am just missing
it. I have also ensured that no cells use any Conditional Formats, as
that seemed a likely candidate, but it was not the problem.

The problem apparently has nothing to do with Precedents or
Decendents, because none of the cells in question reference or are
referenced by any other cells.

Can someone please shed some light on this frustrating situation? Is
it documented anywhere that Validation and Comments suppress the
natural function of the Change events? If so, is it also documented
that there are other properties that will do likewise?