Basically: 

I'm using the official endless mod.

[Endless Mod][Contemporary][Turn pending].ctr

This save will encounter the Pending turn bug at the end of the turn. The interesting thing about this is that it retroactively caused a bunch of my other, earlier, saves within that same session to also encounter the end turn bug on reload. 

Simply load that save file, then end the turn. What should happen is that the game becomes stuck within the pending turn load.

[Endless Mod][Industrial Era][Great Apes].ctr

This is the latest save where I could still play out the turns in industrial era and get farther than the contemporary save file, however, only if I'm still in the industrial era. After going contemporary, the save shortly gains the end turn bug.

Load that save, then continue on with the game. What should happen is that you are able to stay in Industrial era and have no problems playing past the turn where the contemporary save breaks. After going into the contemporary era, things get fickle on when the pending turn bug starts to happen (Probably within 5 ish turn after evolving into contemporary).

It's 5/10 Reproduceable for the Industrial era save file, although  it's 10/10 Reproduceable for the contemporary save file.

I would have uploaded the Diagnostic files, too, however it seems like something is going wrong with all my file uploads to this sight now, just after having uploaded those two saves.

edit:

HUMANKIND Diagnostic file.pdf

That's the diagnostic file which starts where the Industrial Era Save file is