Error on rendering "unpack requires a string argument of length 8"

Thanks for this project. I am not familiar with the Linux, Python, Git world, but I am OK with using my Windows 10 machine. After a struggle I have managed to install OSGeo4W, and eventually to get MapSlicer to run.

However at the render stage I get the error message "unpack requires a string argument of length 8", and this has happened for each input file I have tried. I note that this was a reported error in 2015 that was solved by using OSGeo Live., and I want to stick to Windows

Maybe there is some version issue? I see I have GDAL 2.1.2; Python 2.7.5 64 bit, and your requisites say Python 2.5 (without a plus). I cannot see what version of wxpython I have.

I have been successful doing tiling using both MapTiler and gdal2tiles already, so using MapSlicer is not essential but it would have been nice. (As feedback I realise that, if I had noticed that OSGeo4W had wxPython as an option earlier, the installation of MapSlicer would have been easier).