tween murder mystery (?) in a hotel in the early 1900s

[phoebe !!]

~ tween murder mystery set in a hotel
~ definitely involved an old-timey elevator as a major plot point
~ blue cover ( i think) with white lettering/ design
~ I think I read the book between 2015-2017 and it was new around that time
~ Set sometime in the early-mid 1900s (very period-based)

[Rainbowheart]

Is the main character male or female?

[phoebe !!]

i think there was a small cast of characters but i distinctly remember a female mc

[Becca]

Can you remember which country it was set in? The blue cover reminded me of The Mystery of the Clockwork Sparrow by Katherine Woodfine, which is set in a department store in Edwardian London (UK) and I vaguely remember something about the lifts / elevators in the store.

It also might be worth browsing relevant lists e.g. YA & Middle Grade Historical Mysteries