Is there a size limit for the description of a simple product in Magento 184.108.40.206? When I paste the description into the Description field, save the result, and then view the product, the last 30% is being chopped off.
In a clean install of Magento the description is stored in the value column of the catalog_product_entity_text table.
The value column is a text field which has a memory limit of 65,535 bytes (see https://stackoverflow.com/a/6766854/1410540)
I would try and see if I saved 50% of the description on a dev/staging does it save and if it doesn't save fully then I would look at disabling all 3rd party modules and seeing does it save then and start debugging from there.
I would also enable logging before saving again to see does any exceptions are being thrown.