I vote that Mikey has uncovered a valid bug.
Both mechanics were released at the same time. From personal experience I know that when developing with different teams, not every tiny detail is communicated and the scrolls may have something embedded that prevents the return to inventory when picking up the container to properly handle the contents. (whew, long sentence, must catch my breath)
There may be other items that share that trait, but, to my knowledge, no one else has posted about it, and certainly the devs//QA did not have enough time to test every item in game.
Mikey has discovered it and unless someone has experienced a different result using the same conditions, it deserves a place on Trello. If similar results with other items are found, reporting them here would help the devs localize the specific cause.
For now, we have @Vattende’s workaround to empty all containers prior to returning the container to inventory and @Kwalya’s help with narrowing the parameters, along with Mikey’s detailed report including his additional testing.
As far as describing it for Trello, this is a suggestion based on Mikey’s OP …
When returning a chest to inventory, Unnamed City Scrolls will disappear.
(since the cards limit the description length)
PS: if you carefully read the patch notes the top section says “return to inventory” but in the details below it says the contents will be in a loot bag on the floor. It may be the ‘return to inventory’ was a relatively late addition since I read the loot bag thing on the TestLive board.