I have a post post relating to this here Carriage 5100 bug?
This bug is still with us I’m afraid, I have made a screen video capture which I can forward to you if you wish? let me know where to send it to.
I enter the carriage category and details and save the purchase, when I then look back in the purchase the category has changed to General Purchase?? I then change it back and it seems to stay put, this now means I am having to check and change almost all carriage entries.