Open the online help and go to the section Conditions; fields and then scroll up
to the top of the text on the right (with the heading Defining Conditions).

Missing from Conditions and Variables sections is an important note saying:
"Note that when writing conditions including numbers they must be by themselves
and strings must be in double quotes.  For example TEST == 1 would be true if
the field TEST contain the value 1.  You could then do TEST + 1 to get the value
2.  If you set the condition to be TEST == "1" however it would fail as it would
test to see if TEST was a string, not a number, equal to "1".

Further down under Conditions and Database Fields there needs to be another
important note saying:
"Note that when using fields with hyphens in the name, they must be enclosed in
double quotes, e.g. "Database.Table.E-Mail".  This does not apply to fields with
underscores in, as Database.Table.E_mail is accepatable"

These two note who have prevented issue 18294 and the final part of issue 15100
being reported when they behave as expected.