recurring not writable issue with folder permissi

-- url of the page with the problem -- : penbyte.com
-- HikaShop version -- : 2.6.1 (bug fix date 1/20/2016)
-- Joomla version -- : 3.4.8
-- PHP version -- : 5.5
-- Error-message(debug-mod must be tuned on) -- : ERROR
The folder /home/penbyte/public_html/media/com_hikashop/upload/thumbnails/0x200f is not writable

Hello, and thanks for your help

I previously wrote to you about this error:
ERROR
The folder /home/penbyte/public_html/media/com_hikashop/upload/thumbnails/0x200f is not writable

I have set this folder's permission to 755, just like the other folders.
For a while i did not receive any errors, but, now the error is back.

I have made changes to global canonical seo setting, but i have not changed anything else,
Any idea as to why this error keeps reoccurring?
thanks