This issue has been happening for quite some time on one of our projects. I haven't been able to find a clear reason for it. We have never been able to replicate it on a different server, so we know it certainly has, in part, to do with the server, but even other installs of different CMSs (like Wordpress) on the same server do not trigger this issue.
The install is a little outdated (EE2.5.5), but I'm not sure I can convince our client to spend the time upgrading the EE install, especially if I can't say with certainty that it'd solve the issue.
This happens on Front-End channel forms as well as Admin Panel channel entries.
What happens is this: If the post is very large (500 words or more) and at some point the word "from" is used in a textarea (wygwam OR standard EE textareas), the post will say that it has "saved" but in fact, the content does not get saved, and the old content persists. It appears to be a XSS prevention (server being concerned about sql injections), but as I mentioned, it only happens for EE data, and not other CMSs.
A friend of mine mentioned that it could be the Apache mod_security, and I forwarded that to the Client's hosting provider, and they said that plugin isn't on the server.
Modules/Extensions involved in this EE install:
- Low Search
- Low Seg2Cat
- Low Variables
- P&T Field Pack
- SEO Lite
- Zoo Flexible Admin
Any ideas? Any more information needed to help? I'm more than willing to provide information to help solve this once and for all.