Thanks very much for trying to help, but I think I am going to try x10hosting as a host instead and hopefully I won't have this problem there. (I originally wasn't using it because I was having trouble getting the confirmation email - but I see now that it has unlimited storage while 000webhost does not for free accounts - so it seems like a good idea to switch regardless
)
P.S. I was able to get it running on x10 (after applying the fix in the sticky) so the problem seems to be with 000webhost somehow. Thanks again for your assistance!