If listing users with custom fields is a one-off requirement or only super users need to do that task from time to time, registered users and the contents of their custom fields can be listed by a custom query using phpMyAdmin or a similar MySQL client.
The following example creates temporary tables before generating the list. The query assumes that there are three custom fields, field4, field5 and field6, where the field ids are 4, 5 and 6. Replace 'epr28r' with your own table prefix.
CREATE TEMPORARY TABLE IF NOT EXISTS `ep28r_registered`
SELECT u.id, u.name, u.email FROM ep28r_users u
INNER JOIN ep28r_user_usergroup_map m ON u.id = m.user_id
WHERE m.group_id = 2 AND u.block = 0;
CREATE TEMPORARY TABLE IF NOT EXISTS `ep28r_work4`
SELECT u.id, v.value AS field4 FROM ep28r_registered r
LEFT JOIN ep28r_fields_values v ON r.id = v.item_id
INNER JOIN ep28r_fields f ON f.id = v.field_id
WHERE f.id = 4;
CREATE TEMPORARY TABLE IF NOT EXISTS `ep28r_work5`
SELECT u.id, v.value AS field5 FROM ep28r_registered r
LEFT JOIN ep28r_fields_values v ON r.id = v.item_id
INNER JOIN ep28r_fields f ON f.id = v.field_id
WHERE f.id = 5;
CREATE TEMPORARY TABLE IF NOT EXISTS `ep28r_work6`
SELECT u.id, v.value AS field6 FROM ep28r_registered r
LEFT JOIN ep28r_fields_values v ON r.id = v.item_id
INNER JOIN ep28r_fields f ON f.id = v.field_id
WHERE f.id = 6;
SELECT r.id, r.name, r.email, w4.field4, w5.field5, w6.field6 FROM `ep28r_registered` r
INNER JOIN `ep28r_work4` w4 ON r.id = w4.id
INNER JOIN `ep28r_work5` w5 ON r.id = w5.id
INNER JOIN `ep28r_work6` w6 ON r.id = w6.id;