I have update VM at last version. Joomla 3.8.2 PHP 7.11
Now in Joomla search don't find SKU code in search and the module VM_search call the result page wrong: in menù I have com_search and I have fill the field itemID with result menù pag but call the wrongpage.
I have change the menù and now the urlrewrite for the product url don't find the product.
Now I have down grade VM and it's work
Do you use a 3rd party software?
no longer work on both administration and frontend searches
Do you use signs like for example # inside product sku?
no..
In my case I can search with the Joomla search plugin for Virtuemart and it finds the products by SKU. I did modify it, so it works with %...% search, I mean not exact phrase too. You may try to replace virtuemart.php in plugins/search/virtuemart/. Please report if that helps. Please remove the .txt so it reads virtuemart.php. The txt is just because it is not allowed to send native php here.
I have the same problem, no longer work on both administration and frontend searches. Please help to solve the problem.