[Koha] Confusion over filtering search results by "current location" of an item

[Chris Brown]

Hello,

Please can anyone explain to me the role of the "Current Location" of an
item in filterng results from searching the catalog (using the staf
interface). The behaviour we are seeing is that items with no "Current
Location" set DO NOT SHOW UP if you filter the seach results based on
"Holding Library". On the other hand, if you use the "Advanced Search" and
select a specific library, items with no "Current Location" DO show up.

Also, when/how does the "Current Location" get set and how do you edit it?
(The screen for editing items lets us change the "Permanent Location" but
there is no column for "Current Location".)

Any advice much appreciated. Let me know if you want me to explain this
better! We are using Koha 19.11.

Chris Brown (Voluntary Libraries in Sheffield)