Looks like Quick Adjustable Inserters makes entity.pickup/drop_location use 1 and 2 instead of "x" and "y" as keys. I was able to fix it by just adding a line in each swap in flip.lua to check if the alternative key should be used and use it if so.

Thanks for reporting it.
I have not yet been able to revise the complete code, too many changes in the new API.

Have same error with "Side Inserters" mod if I try to mirror adjusted inserter

Error while running event Kux-BlueprintExtensions::on_gui_click (ID 1)
Kux-BlueprintExtensions/actions/flip.lua:204: attempt to perform arithmetic on field '?' (a nil value)
stack traceback:
Kux-BlueprintExtensions/actions/flip.lua:204: in function <Kux-BlueprintExtensions/actions/flip.lua:158>
(...tail calls...)
Kux-CoreLib/lib/EventDistributor.lua:157: in function <Kux-CoreLib/lib/EventDistributor.lua:151>

fixed. I don't know if this fixes all inserters, but I have fixed a reading issue with possition.

fixed. I don't know if this fixes all inserters, but I have fixed a reading issue with possition.

Now BP mirroring and rotation works fine. Thanks a lot man!