"developer options not available for this user" Marshmallow

Question

I'm experiencing very interesting problem with my Galaxy S6 Edge phone with marshmallow. When I go to developer options. Instead of a long list of options I get a message of "developer options not available for this user". As far as I know, I don't have any other user (I even don't know how to add a user, to be honest). I saw a couple of people had a similar issue with kitkat but they weren't even able to get the developer options menu item in the settings. I have that developer options item and I actually have it for a while. I haven't done anything special recently and I wonder anyone experienced this before and whether there is a way of fixing this without factory reset.

Finally there are a couple of more symptoms which may/may not be related with this. Task Switch button at the bottom of screen doesn't work. The settings button on the notifications panel doesn't work

EDIT : I had to fix the issue by factory reset, I didn't have the chance to try Victor's answer but I am accepting it as the right answer since there are some people who were able to fix their issue

Answer 1

One solution is to run the com.google.android.setupwizard/.SetupWizardTestActivity activity and step through the setup wizard - https://plus.google.com/u/0/+PaulOBrien/posts/8EGNvpY9jQa

A relatively easy way of running that activity is described here: http://forums.androidcentral.com/samsung-galaxy-s7/659407-s7-edge-not-showing-notifications-tray-recent-apps-button-settings-button-dnt-work.html#post5083902

1) Download Nova Launcher & set it as default to replace TouchWiz.
2) Long press on the home screen.
3) Choose Widgets.
4) At the top, under Nova Launcher, scroll to the right & press & hold on Activities and place it somewhere empty on the home screen.
5) Scroll down to Setup Wizard. I saw 2 Setup Wizard options.
6) Under the first Setup Wizard option, I opened it & scrolled down to the 3rd choice which said ".SetupWizardTestActivity". It might be in a different spot for you, but look at the small writing, that's how I saw this one.
7) Select that to create the widget shortcut.
8) Open it. Apparently you're supposed to have a menu to go through and just click through "Next", but there wasn't one for me.

Following the instructions in that forum post fixed the problem on my Note 4.