I think there might be a bug in handling of Drop Down Multiselect Items.
In my CB there is a CB field, type Drop Down Multi-select, with more than 90 values.
In order to keep things tidy, I defined Group fields A - Z and sorted the field entries respectively.
When I try to add new entries, several values (starting at approximately ID #76) appear incomplete, as the "Group"-selector is not properly set. This happens even though I set this value correctly in my last session and saved the CB field successfully:
In the database table "comprofiler_field_values" the entries are stored correctly with "fieldgroup" set to "0".
However, when I re-open the field for editing within CB fields settings, the values are missing again.
In order that I can save changes, I have to re-select the proper Group-values. But as soon as I open the Drop Down field again for modification, the same items are "ungrouped" again.