I created fulfillment service with permits_sku_sharing: true, inventory_management: true.
It should be update at the available field at OCMS row, instead of the first row default location.
We can confirm the same issue with the current api version (2022-07).
At the moment my workaround is to make the InventoryLevel from the FulfillmentService exclusive and remove all others from the InventoryItem.
I have not yet tested what happens if I now add an additional FulfillmentService.