Analysis:
Range analysis detects that the subquery is expensive and doesn't
build a range access method. Later, the applicability test for loose
scan doesn't take that into account, and builds a loose scan method
without a range scan on the min/max column. As a result loose scan
fetches the first key in each group, rather than the first key that
satisfies the condition on the min/max column.

Solution:
Since there is no SEL_ARG tree to be used for the min/max column,
it is not possible to use loose scan if the min/max column is compared
with an expensive scalar subquery. Make the test for loose scan
applicability to be in sync with the range analysis code by testing if
the min/max argument is compared with an expensive predicate.