Can this problem be reproduced with the official owncloud server?
(url: https://demo.owncloud.org, user: test, password: test)
Android version: 7
Device model: Nexus 6P
Stock or customized system: Stock
ownCloud app version: master branch
This UI bug was introduced via https://github.com/owncloud/android/pull/2442 when changing:

@davigonz I will fix this.
I will fix this.
Sure, go ahead!
@davigonz I am unable to determine the reason why the "Select-all" and "Select inverse options are appearing in the top of the file actions menu as everything seems to be fine. One way to fix this would be to shift back to android:showAsAction from app:showAsAction should I do that?
I have tried to solve this problem but I have encountered a bug.
Apparently, there is an error in logic. When you press the "select all" option in the menu, it option appears again in the TopBar. From what I've seen, the ActionMode update and the mEnableSelectAll variable are not setting well.
I think this is the first step to fix this issue.
I am unable to determine the reason why the "Select-all" and "Select inverse options are appearing in the top of the file actions menu as everything seems to be fine. One way to fix this would be to shift back to android:showAsAction from app:showAsAction should I do that?
Yes, let's solve it by doing that.
I have tried to solve this problem but I have encountered a bug.
Apparently, there is an error in logic. When you press the "select all" option in the menu, it option appears again in the TopBar. From what I've seen, the ActionMode update and the mEnableSelectAll variable are not setting well.
I think this is the first step to fix this issue.
Thanks @deandreamatias for your report, I was able to solve this locally by replacing app:showAsAction with android:showAsAction so I guess that what you refer to is a different bug, could you open a new issue and give us more details?
@davigonz I have also been able to replicate this comment should I change it back to android:showAsAction?
Yes, try to use android:showAsAction, I answered you in https://github.com/owncloud/android/issues/2493#issuecomment-478575429
Fixed!