Attributes are not changing in the placed order I have a commerce site with T-shirts as products. I have added custom attributes of size and type.

By default L Size is selected. But even if the user changes the size to something else say M or S, in the order that is placed the size is still being shown as L.

I am assuming that this is because of caching. I currently have authcache enabled with Mem-cache in the backend. 

I checked the XHR call that is being made. I see that the size that is being sent in the call is the one selected by the user. But however when the order is placed it still says L. Any help where to start debugging would be greatly appreciated.
This is a known issue with page level caching system for anonymous users in Drupal. Please subscribe to the open issue on the authcache issue tracker, then you will be notified as soon as this is fixed. There is also a report in the Drupal Commerce Queue