OK I did some testing. First I triggered the bug by adding a book to a list and then removing it. For some reason removing triggers the bug more often.
Code:
Action Chains: Starting chain: View Column Sort
Action Chains: View Column Sort: starting action No. 1: View Column Sort
DEBUG: sort_order: [['#onreadinglist', True], ['#readorder', True], ['#currentlyreading', True], ['#percentread', False], ['#lastread', False]]
Action Chains: Is db modified by chain: False
Action Chains: chain (View Column Sort) finished in: 0:00:00.078262
For comparison, here's a book that I hadn't touched and thus isn't affected by the bug and sorts normally. It shows the same order. (I'm not sure what true/false mean in this context; both books have a #percentread and #lastread value.)
Code:
Action Chains: View Column Sort: starting action No. 1: View Column Sort
DEBUG: sort_order: [['#onreadinglist', True], ['#readorder', True], ['#currentlyreading', True], ['#percentread', False], ['#lastread', False]]
Action Chains: Is db modified by chain: False
Action Chains: chain (View Column Sort) finished in: 0:00:00.078130