H2 version 2.0.204

This issue applies to both VARCHAR_IGNORECASE columns and databases opened with IGNORECASE=TRUE

CREATE TABLE TEST (S VARCHAR);
CREATE INDEX TEST_S ON TEST(S);
INSERT INTO TEST(S) VALUES ('A'),('A'),('B');
SELECT S FROM TEST GROUP BY S;
-- output: A,B (as expected)

CREATE TABLE TEST (S VARCHAR_IGNORECASE);
CREATE INDEX TEST_S ON TEST(S);
INSERT INTO TEST(S) VALUES ('A'),('A'),('B');
SELECT S FROM TEST GROUP BY S;
-- output: A,A,B (not expected)