Hello!
I have simillar problem to #8 and #10 but window.pushGLStates() and window.popGLStates() doesn't help. I'm rendering my scene to texture and then try to display it in imgui. It start to bug on renderTexture.display() method. I call it before ImGui::Render()

    renderTexture.clear();
    map->render(renderTexture);
    simulation->render(renderTexture, delta);
    renderTexture.display();

    ImGui::SFML::Update(elapsed);
    window->clear();
    gui->test();
    gui->render(sprite);
    ImGui::Render();

In test() and render(sprite) i call just imgui functions.
I'm using 2.4 sfml version.

Thanks in advance for help :)

EDIT:
It turns out that i don't have to use renderTexture.display() and then everything is fine.