What is it with the disappearing bike stands outside the Guildhall in Bath?

Months ago l noticed one ‘hoop’ was missing from a cluster of three stands to the left of the steps and now – yesterday – another one has disappeared.

This time from the middle of the grouping right in front of the building.

Are these stands made of a precious metal ?Are they being stolen for scrap? Or is there a less sinister reason why they are disappearing!
Does anyone know?
Due to the narrow base & the wholly inadequate hilti bolts, it only takes a slight lateral load such as a push or a kick to shear the bolts. They look pretty, but aren’t really fit for purpose.