Sorry for this unusual delay since I have been busy with multiple released and have been unable to replicate it in our dev machines – you will hear from me within next few hours.
The issue is due to a plugin named Search and Filter Pro since it is using a different page template to display search results. I deactivated the same and used another plugin to add a search field to menu and things are back to normal. Sorry about the delay – we took quite a bit of time to attend to this.