Jdiction is certainly an amazing extension for joomla.
I have this same problem and after scouting the forum it appears the problem has to do with the latest versions of the default Editors of Joomla, i.e. TinyMCE and MirrorCode because the problem is rampant with J3.20.
In my case when i choose No Editor in global config, jDiction works absolutely well. but with either TinyMCE or MirrorCode, only titles' translations are saved, the 'body text' is not saved. And without a WYSIWYG Editor, creating pages becomes difficult.
Our very kind developer has said he's going to look into it, but when? I hope soon.