master/Detail (Strange behaviour)

Hello.
I am experiencing a strange behavior on a form Detail.

i have this hierarchy:
Form1>;Form2>;Form3

Form1 is Master for Form2 ; Form2 is Master for Form3. So in the Form1 i can see a cascade of records both of Form2 and Form3

the relationship between Master and Detail is one-to-many.

In the properties of the Detail Form2 (Master/Detail properties) I enabled the option “Enable Navigation Button in the target application” for the Form3.

Despite often in the Form3 there are for example 3 or 4 records associated with a parent record of the master table Form2 , the navigation of the Form3 (either the one with the arrows< >; or navigation pages) only shows me two records to navigate.

It happens then that if I add another record in the Form3, suddenly unlocks, letting me browse all the details records in Form3. But when i reload the form or generate the app again the problem is there again.

Can’t underestand why is this happening.

Thanks