I've got around 58 items and things start to act up.

Firstly, on back end, after I batch edit (open all items at once) items and click "apply", the spinning icons will just keep spinning, I had to refresh the page and all the changes I made is lost.
Secondly, since the batch editting didn't work, I edit the new items one by one and it went through. But after I closed the module and reopen it, some of the new items are not showing in the list, although on front end, all items are showing and also in the database the new items are still in there.
I saved the module two times, each time something got lost. The first time I saved it all of the items' names are lost. Btw, I believe those names were still existing in the database, but after I saved the module a second time, the names are lost permanently.

Now I don't know if this issue has to do with too many items but I've never encountered such problem before when usually my items are less than 20. So too many items causing this is a good guess.

What do you think this problem might stem from?