When adding a lookup to the filter of a list/grid view that contains a BROWSE-ONLY clause, it effectively removes from the selection any value that does not meet the criteria defined in this clause. This makes it to where the filter is unable to be used to filter for some values that have already been used in some objects instances on the list.
Release : Any
This is the expected behavior when BROWSE-ONLY is used in a lookup query. The parameters defined within this clause are taken into account when searching for the values in both the filter and the field on the object instance properties. The parameters defined within this clause are only ignored when displaying an already selected value on an object instance.