Custom fields not showing at admin UI, after upgrade to VM 3.0.18

[cvrak]

Hi,

I've just upgraded  to VM 3.0.18 and facing a problem with product custom fields at administration: At "custom fileds" tab, from the dropdown list I select a custom field but nothing happens, no extra fields are displayed. All extra fields are created before upgrade.
My site runs with Joomla 3.6.2 and PHP 5.6.26

Can anyone help??
Thanks