Article ACL automatically changed after SAVE

[pico]

Hi all!
I have a JOOMLA 3.x WEB site updated to latest release (3.10.3)
I have discovered just few days ago that NOW (I do not know what update have introduced this issue!) that if I edit an article from frontend as a Author or Publisher User, when I push to SAVE button JOOMLA automatically change the ACL of the content\article I edited.
THis cause the article itself to be edited only by a SuperUser.

The SAVE action, shortly, change the ACL of the article and due to this, the Publisher cannot edit anymore.
Does anybody know if this is a known bug or how can I investigate to resolve this ?
For your info, I'm using also SP Pagebuilder Pro (version 3.8 or 3.7.9)
I have also disabled the "article integration" of SP Page Builder, but the problem is not gone!
Please, help me because this is quite frustrating .
THX