Optimizer Context is empty for EXPLAIN that uses a table

CREATE TABLE t1 (a INT, b INT, KEY(a));

INSERT INTO t1 VALUES (1,1), (2,2), (3,3);

# Note: this is essential: without it, the context is present:

analyze table t1;

create function add1(i int) returns int deterministic

  return i+1;

set optimizer_record_context=1;

explain select * from t1 where b< add1(3);

select * from information_schema.optimizer_context;

drop function add1;

DROP TABLE t1;

explain select * from t1 where b< add1(3);

id      select_type     table   type    possible_keys   key     key_len ref     rows    Extra

1       SIMPLE  t1      ALL     NULL    NULL    NULL    NULL    3       Using where

select * from information_schema.optimizer_context;

QUERY   CONTEXT

drop function add1;

DROP TABLE t1;

  if (!thd->opt_ctx_recorder ||

      lex->query_tables == *(lex->query_tables_last))

  {

    return false;

  }