It looks that mssql driver developer didn't test how it works on custom schemas:
One of the bugs is that foreign keys wont be displayed if table is in custom schema.
Following change should fix the problem (just for foreign keys - not for other problems):
adminer/adminer/drivers/mssql.inc.php
In line 542 you find:
foreach (get_rows("EXEC sp_fkeys @fktable_name = " . q($table)) as $row) {
should be:
foreach (get_rows("EXEC sp_fkeys @fktable_name = " . q($table) . “, @fktable_owner = ‘’. q(get_schema())) as $row) {
