Smart Update Pinger – Posts not showing up

Hi,

I am using Smart Update Pinger.
Here is the list of services I ping:
https://blogsearch.google.com/ping/RPC2
https://ping.blo.gs/
https://ping.feedburner.com
https://rpc.pingomatic.com
https://rpc.weblogs.com/RPC2
https://www.blogpeople.net/servlet/weblogUpdates

The logs show that every ping is successful.
However they don’t show up in google, even days later, when I search with the blog title, which is always quite unique.
I have an older install of WordPress on an older server (cannot update). Posts are showing up in Google within hours…

The feeds are pulled from RSS feeds, the point is precisely the ping and SEO benefits. The posts are never edited or pinged manualy afterward.

Do you have any ideas of what the problem might be, or how could troubleshoot this?

Thanks!