Timelion - Adding two time series with filters not working as expected

This is working as expected (in the sense, that at a given time t,
a+b graph does have value of sum of a and b at time t.

.es(index=index-*, q=''condition_a').label("a"),
.es(index=index-*, q='condition_b').label("b"),
.es(index=index-*,q='condition_a').add(.es(index=index-*, q='"condition_b')).label("a+b"),

However, this does not (i.e. at time t, the value of a+b is not equal to individual values of a and b)

.es(index=index-*, q=''condition_a AND condition_c').label("a"),
.es(index=index-*, q='condition_b AND condition_c').label("b"),
.es(index=index-*,q='condition_a AND condition_c').add(.es(index=index-*, q='"condition_b AND condition_c')).label("a+b")

Any help?

Hmm, that does seem odd. Do you mind sharing a screenshot?

Also do you intentionally have two single quotes before condition_a and a double quote before condition_b in some of the above?