Details in our client area.

I would need more information on exactly what was set. I set this from 20 seconds to 18 seconds and it saved with no issue

It's the guest search flood setting.
Currently set to Unlimited. If we try to set it to a value, f.ex. 10 seconds, it fails.

Please could you confirm which site, as its currently set to 18

It's our main site, I only see this if I click on "Client area".
Domain ending with "n", not "a". (Which is a closed support site)

I have created a ticket for you on this, and someone will be in contact as soon as possible

This is a known issue that was fixed in 4.7.16

We are running 4.7.15 which is the last revision.

4.7.16 is currently in beta.  Once it is released, the issue should be fixed.  🙂