Custom field values don't display on order form.

[its4yougr]

I have installed VM 3.0.14 (latest) on Joomla 3.6.2 here www.esorouxa-busto.gr using the Gavick InStyle template with template overrides. On the product page it shows the custom fields OK and the visitor can choose w/o a problem. I used position "ontop" for the custom fields and I have also set the position "ontop" to all custom fields.
When someone makes any selection (i.e. size, color) and places an order, his selections don't show on his order in the backend and this way the shop owner doesn't know what color, size etc to send. It just displays the product name and SKU and no values on any of the custom fields chosen. It's not either in the email he and the store owner gets after the order.
Note that: The custom fields, that we need to get their values, are marked as "Cart Input" and "Cart Attribute" and I am using the Multiple Custom Fields Filter for VM (http://extensions.joomla.org/extension/multiple-customfields-filter-for-virtuemart) which works more convenient for me for the custom fields.
I have found this thead : http://forum.virtuemart.net/index.php?topic=126629.0 where the problem was corrected by changing a line in the productdetails/default.php file. I tried doing the same thing but didn't work.... I checked also the jos_virtuemart_order_items table where the field product_attribute has just two brackets ([]). It doesn't take the values of the custom fields after the order is placed.
What I also did was to rename the folder com_virtuemart inside the template/html/ folder (template overrides) to have the original VM files load but that didn't work either. Therefore it's not a template issue.

Where should I search and why it's not working; Please Help....

Thanks

[its4yougr]

Hi again
In order to troubleshoot the problem I did the following so that I eliminate some factors:
1. I renamed the folder /templates/mytemplate/html/com_virtuemart to /templates/mytemplate/html/_com_virtuemart so that I don't have any template overrides. The problem still exists.
2. I disabled the Generic OnePage Check out that I use. The problem still exists.
3. I reinstalled Virtuemart 3.0.14 (latest version). The problem still exists.
4. I reinstalled the Virtuemart 3 Product Filter by Custom Fields that I am using and is Virtuemart 3 compatible again. The problem still exists.
5. I installed Virtuemart 3.0.16 (Latest Stable version ??) but the problem still exists.

Please note that on every of the above steps I cleared site and browser cache....

I cannot uninstall Virtuemart and reinstall it again since there lots of products already there configured with their custom fields.

Is there anything else left to do? Please advise...

Thank you in advance

[its4yougr]

Hi again
No one had the same or similar problem?
It's just me???

Please respond with a suggestion on what to look for or how I can troubleshoot that problem... I think most of you are a lot more experienced than me...
Thanks