This sounds very much like a problem with your PHP settings. What are your max_vars settings in PHP? If it is too low, they input can get cut off.
*PS. limesurvey 2 admin environment was much less buggy! The fact that I need to ask on the forum for such a simple question proves the newer gui is less usable for users...
Which LS 2? LS 2.06LTS or LS 2.5x/2.7x? The later was basically just as buggy as LS 4.x in the same state.
We currently recommend LS 3.x LTS for productive use, I wouldn't consider LS 4.x ready for productive use. On the other hand, you are using a more than 6 months old version of LS 4.x, no wonder it is buggy. You skipped I don't know how many updates since (not saying that there are no bugs in the most recent version, but in yours there are certainly more...)