Hide Setting for Navigation button doesnt work properly on F|L|OSS Browser

Expected behavior

When i turn on Hide always setting for Navigation button then this button should be hidden.

Actual behavior

Navigation button is still displayed although Hide always setting has been turned on.

How to reproduce

• Download F|L|oss browser then use it to open a website. By default, you can see navigation button(the yellow button) appears when you scroll down.
• Go to Settings-> Behaviour/UI and click on Hide in Navigation button section.
• Select Never Hide.
• Go back your homepage, as you can see, Navigation button is always displayed without any scrolling needed.
• Go to Settings-> Behaviour/UI and click on Hide in Navigation button section.
• Select Hide Always
• Go back your homepage, as you can see, Navigation button which should be hidden now is still displayed

Testing Environment

• Browser: F|L|oss browser 5.6
• Operating system: Android 7.1.2
• Device: Xiaomi Redmi5

Recording Of The Bug

http://www.dailymotion.com/video/x6it12e