In-Portal uses advanced data filtering system, where developer can define filter type that will be used for each field being displayed in grid.
For example "grid_options_filter" block will produce SQL like FieldName = ID1, when in used. On the other hand block "grid_picker_filter" will produce SQL like FieldName LIKE '%|ID1|%' when used.
I've noticed, that when "grid_picker_filter" block is used, then I've got warning what it 'options' type filter is undefined for that field. That's obviously is a copy-paste error, since that filter was copied from "grid_options_filter" at some point of development.
Ready for testing.