The portal updates itself after saving an entry. If the "internal ID" of the entry was changed, this "in place re-rendering" leads to the entry missing. Either fix that. Or disallow changing the ID. I think that would be okay.
Just to be clear: A reload shows the entry again. It is not completely lost. Just not visible after the "in place re-rendering".
*** This bug has been marked as a duplicate of bug 49526 ***