Hi, everyone
Firstly, I have to say that I am not an advertiser, but the end user of prestashop. My business has been using prestashop for years from v1.5.6.2 and we upgraded to 1.7.6.1 at the end of 2019. After 4-month live testing, everthing is ok now.
I myself had same problem before about 'offers, review or aggregate ratings' and tried to get answer from prestashop forum, but finally it proves a big waste of time. Also, I did try to edit the file according to microdata markup guide. Unfortunately, I failed again although it is a piece of cake for programmer. For me, it is impossible mission.
Finally, I found a module which did a greate job, although it is not a perfect one. However at least it cleaned all the errors showed in google search console.
The link of this module is below: (it seems the price of this module goes up, previously it was only 59 dollars). Please take a good look at this module decription before purchase and make sure this module can solve your issues. Do not waste you money, although I did many times
If you believe me, do not waste your time and get this module to clean everything. After it, you need to know the following things as a friendly reminder:
1. prestashop is not perfect and it is going well. But next time, I am preparing to use Magento platform instead because it has strong Seo function compared with prestashop.
2. This recommended module can not solve everything. But from this module, we can learn how to solve this problem manually and the developer of this module did a good service, at least I had good experience with the developer.
3. Do not expect too much. This module can not remove all the warnings which will not have any harm on your web. But, still we can learn how to delete warnings from this module.
4. This module could have some conflicts with other 3rd party modules, like seo modules. I used Advanced Seo module to optimize my web. In fact, The conflicts will not cause big problem. So far, they both work in their own way.
5. This module will modify your files. But it create a backup file to tell which files have been changed and how these files have been changed. You need to test your web again after installation to make sure all other functions are running normally. I had one problem with my shopping cart after installing this module. But from the back up files, I changed the shopcart.tpl to the previous status. Now, all the basic functions of my web are good.
Hopefull, my answer could help you guys. I know your bad experience with this problem which I had previously and tortured me at least 3 month without good sleep at all.
Best regards