Why order cannot bulk update?

The process is designed to pick the order and update the pick status as you pick the products using Picking Mobile App. Alternatively, if you are using picklist for picking, then you can enable the bulk processing from the Warehouse Setting >General> to scroll to B2C order settings and tick the Bulk processing box. 

We hope the details above were helpful for you. Please feel free to share with us if require further assistance and will be happy to take it up.