Hi,
I do see the main menu color changing when I go in the shop menu. But that's something handled by your template not HikaShop, so I don't see why it would do that because of a HikaShop update.
However, I see that on the page, the sub menu is also broken:
monosnap.com/file/pmqjfldRuj8fXMFmyLt2jyzA2o97Bh
And there are many javascript errors:
monosnap.com/file/LueuakjAxvi5UkQnpSxKi8Wv65fmYt
These errors seem to come from a jquery conflict, probably linked to the template too. And that's probably why the sub menu area is broken.
Now, usually, in such case, the first thing I would recommend is to install jQuery Easy for Joomla and configure it so that it can fix the conflict:
extensions.joomla.org/extension/jquery-easy/
But I would also recommend to check with your template provider. Maybe you need to update your template or maybe these are new issues they don't know about.