I have had a somewhat similar issue with EE 1.7.3
We just switched servers over the weekend... we had been on the previous server for about 5-6 years. All worked well.
Then we put up a couple entries in different weblogs (now "Channels" in 2.x) and noticed that, even though you could put them up in the EE control panel, they did not appear on the website. ??
You could put up entries without problems. They showed in the EE preview.
The entry data was placed in the database in the correct tables (checked).
The entry did NOT show up on the web page. Yet no code had been changed.
IF, however, I changed the Limit="__" number from whatever it used to be (7 or 22 in the main two cases), the new entries showed up.
So on one template I changed the Limit="7" to Limit="8" and the other from Limit="22" to Limit="21" (a smaller number just to check) and, lo, it all works.
I'm not adding the code in here simply because the code is basic and has not changed in years. The only change was the server. Yet EVERYTHING works but that.
Why this happened / happens, I do NOT know.
Just letting you know that it does.