Robin
Is this a known bug that has crept in?
No idea, have never used this tool you mention. But if you urgently need a hex editor: antiX comes whith mc preinstalled, which includes a hex editor you can use out of the box without installing anything additionally. (highlight the file in mc, then press F3 (view file) → F4 (toggle between ascii/hex) → F2 (toggle view/edit mode), in this order.
Btw, how, from what repo or package and on what exact antiX version (sysvinit, runit, 32bit, 64bit, full, base, core…) did you install the tool? It looks like the system libraries it has been built against don’t match what your system runs on.
Windows is like a submarine. Open a window and serious problems will start.