Index advisor suggesting a non-optimal index

https://forums.couchbase.com/t/index-advisor-suggesting-a-non-optimal-index/28484

SELECT * FROM example WHERE META().id > "2ebf1fe2-a5b3-48dd-a5e5-051958f81902" AND _class = "org.example.Example" ORDER BY META().id ASC LIMIT 1000

The index advisor is advising an index that looks like this:

CREATE INDEX adv_class ON example(_class)

With the advised index the query takes 10s+ with some 600k documents.

with a manually created index

CREATE INDEX manual_index ON example(_class,(meta().id))

the query takes only around 50ms. Why does the index advisor suggest such index?