Since the last patch, my mining tools disappeared? Are they not loaded anymore? I liked them a lot, preferred them over other axes. Playing with Bob's and Angel's...

Oh dear, I've made a mistake in the loading of the poles and tools. inside the if condition the wrong variable was checked (it missed the PaA-.) 1.15.17 should work correctly.
Sorry if you lost your tools in your save.

No problem, it happpens, ye I lost them in the save, however, they still don't appear in my game (can't craft them / find them).

I believe the problem to be that the prototypes need to reload. I've forgotten to add a migration for the newest version. running the following command should fix it, it resets all prototypes:
for i, force in pairs(game.forces) do
force.reset_recipes()
force.reset_technology_effects()
end