" If I 'screw' the .43x wide angle comverter w/macro, then I am able to see the image."
OK slowly now, is there anything screwed onto the front of the lens? Anything? Remove any and all whatevers from the front of the lens. Is there anything attached to the back of the lens? Remove it too. You should have just the lens no add ons, no filters, no lenses. Nothing but the EF-S 55-250mm f/4-5.6 IS STM itself.
Reset your camera to factory. Menus, tools, clear all settings and clear all custom settings.
Now mount it to your camera and try it. Lens switch in the AF position. Camera in P mode on the dial. ISO 200. One shot mode. Do not use Ai-servo. Go outside on a nice sunny day and take several shots of various subjects. Maybe a nice park. If it works, it works and there is nothing wrong with your gear. If it does not work the lens is faulty. Replace it.
Do the test exactly as I have stated it.
EB
EOS 1DX and 1D Mk IV and less lenses then before!
