Empty Form Tabelobject with all records selected

LO software: Base more versions 5.xx 4.2 have unexpected behaviour User error or real bug?
OS software Ubuntu 14.04
RDBMS users all know a sort of selection form, which is a graphic nice tool to select/deselect records in a table holding selections. Realized by a form with 2 tabelobjects left one showing available records and right tableobject showing selected records. I made this with LO Base and all works almost OK, except when all records are selected the right tableobject is empty, which is unwanted, unexpected, and not to understand.

I could deliver a table to show the behaviour, which I think for the moment is not as designed, not only by me, but also not by Base.

I will attach an example db here to let anybody know, what I mean. Hopefully I will get a reaction then.
The link which I hope gives access to my example DB : http://jaapaap.noip.me/~jaap_aap/EKBasklibo.odb
Instructions :
If you are asked to enable macro’s you have to, or you cannot see what I mean.
You are shown the open Form which is I think very Intuitive.

Diagnosis up to now:
The Form “Favailable” has 1 Mainform and 1 Subform… The link fields are empty and unused.
However I suspect these link fields of causing the trouble.
I made another Form designed with 2 Mainforms. This problem does not exist then any longer.
However then I experience another problem: How to reference the 2nd Mainform?
Law of equal trouble, or what is it called in English? Sure, ecI hope someone can shine a lighton this