Post text not appearing

I have a very odd problem with WordPress. Some of the posts that my authors write do not appear when we hit preview. I have also tried making it private and posting it, and it still doesn’t appear. Originally we thought it was word count, so we tried to cut down the articles significantly, which ended up working, but other articles with the same length as the shortened article weren’t appearing either. For reference, the articles are around 2000-3000 words at most, but sometimes articles less than that won’t appear either.

To test it, I would create articles and copy/paste random gibberish and that appeared (and that had about 6000 words).

We originally had 3.0.4 but we upgraded to 3.1.2 and it’s still not working.

Help is definitely requested as it is getting frustrating for all of us to have to edit articles to make it fit.

Thanks.