Hi,
I can assure you this is a Virtuemart thing, you may try it with the original Virtuemart (with using joomla beez_20 template) the result will be the same.
I will tell you why it behaves like that, you may come up with a tricky solution that works for you.
Let's say, you have this ordering product settings in the backend:
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In the frontend, once you first open any category page. the products will be sorted by "Product Name" and there will be an option to sort them "by price", which is normal. Everything is fine.
Attachment Pasted_Image_11_13_13__5_55_PM-6.png not found
But things are getting acting weird then if you click the "sort by price" drop down link.
If you sort the products with any "other available" sorting option. (it is "by price" in our case). Then there is no way to get back to default sorting (which is "by product name" in our case). Because the cache gets involved (which is ideally good way but creates problem some cases) and the URL don't get updated to get back to default sorting.
The solution is, changing the "default sorting" to "Ordering", which uses the official sorting that you sort products in the Virtuemart backend manually (
VM Backend >> Products >> Products)
Attachment Pasted_Image_11_13_13__5_59_PM-10.png not found
and select "Product name", "Product by Price" and
(optional) "Ordering" options from the available sorting options section.
Attachment Pasted_Image_11_13_13__6_02_PM-4.png not found
So by this method, once you sort product "by price", then you will have the option to sort again by "product name". BUT YOU WON'T BE ABLE TO GO BACK TO "ORDERING" (which was the "Default sorting")
Understand the idea? If the "Ordering" and "Product Name" are exactly the same. Then there will be no problem. You can't get back to "Ordering" but you can go back to "by product name" which are actually the same things.
anyway, do some tests and try until you get the best solution
This is not a patch. It is the tricky way (that i have found out) to solve the problem without core VM hacking.
Regards.
Support.