From this thread https://community.progress.com/community_groups/rollbase/f/25/t/17754.aspx
In release 4.0.0 this problem just fixed "button is disabled when change view".
But when changing page the Attaching multiple records button still dissappear.
Is it bug or not?
Yes, it is a known issue. We have a defect for this. Fix will be available in next major release.