Update: logged back in again, deployed each of the five tripwires in turn. Could see EACH of them in proximity when tabbed-into inventory. None of them were invisible. However, none of them had a nade slot. Couldn't attach anything at all.

Can confirm I had this bug in February several times on Vanilla official and on modded. Also getting it now on 1.24 but not caused by DayZ updates (as Dayzrunner suggested above). Here's what happened: