In module AOS_QUOTE and AOS_INVOICE the option for grouping Line Items is gone. Neither the Group Name, nor adding other groups, nor calculating group sub-totals and totals is here anymore.
I used 7.9.3.0 before and switched now to 7.9.5. I checked the php files of AOS_Line_Item_Group from both versions and they are identical. The vardefs, language, and module .php for AOS_Quotes, AOS_Invoices and AOS_Product_Quotes are a bit different in each version. However, the numbers of Line_Item_Group is the same mentioned everywhere.
What can I do to get the groups back?
And once done, how can I get custom fields such as Start and End Dates in the group?
Help is really much needed and appreciated. The solution can be a bit more difficult, I have a guy who knows PHP well, but still could not fix the problem. Still, he will be able to help me.
I don’t know where you found that answer, but thanks for posting it back here for future reference.
Remember that config_override.php overrides configurations in config.php, so you might want to check both those files to see why your settings were giving you problems.