I created two Multi-Select Query input controls A and B, where B depends on the selected values of A.
In input control A you can select the possible values as it should be.
But when you select e.g. all values in A, you don't get every possible value that you should get for input control B.
The logs from the server showed, that for generating the SQL for input control B, not all selected values of A get passed as PrepStatement Parameters in the SQL to get the values for B.
That's obviously why there are some values missing in B.
The logs also revealed, that sometimes the prepared SQL for input control B gets splitted into two SQL-statements where the first half of the values of A get passed in the first SQL-Statement and the second half of the values get passed in the second SQL-Statement for B.
That is another a reason, why not all possible values are shown in B.
This problem is not database-system specific. I tested it for mysql, postgresql and MS SQL Server.
This problem shows up when there are 100+ possible values for input control A.