Finding same thing here, I can search by item name without issue (i.e. 8" Wheel Nut) however when searching by item code (i.e. 100-823) no results are returned. I can confirm the item_code field has ‘In Global Search’ selected (by default).
Checked demo.erpnext.com however all the items appear to have the item name and item code being the same (i.e. mobile) so not a fair comparison. Cannot add test item either, so unable to compare. Is anyone able to test and advise?