MARKETPRESS NEXT Button disappears during checkout in most browsers but not all.

Ok. I know that was a long subject.
So, the marketpress checkout has a NEXT button to move from BILLING/SHIPPING ADDRESS to SHIPPING METHOD to REVIEW ORDER/PAYMENT.

In FIREFOX, the button shows up properly. In all the other browsers that I've tried, CHROME, INTERNET EXPLORER, EDGE, and on iPhone (firefox), the NEXT button does not show up.

Since this issue works in one browser and not all the others, I did not do the usual "turn off all the plugins" routine.

But, I DID switch to a standard TwentySeventeen theme. This did not effect the outcome. The same problem exists... working in firefox... not in the other browsers.

This sort of sucks for me, because I'm paying $50 bucks in promos that are running right now... (can't halt them)... and probably most users that might buy something are gonna hit this brick wall and disappear on me... not likely to come back either.

Right after I finish this post I will also grant access to the system.

The theme is not yours, it is INDIGO (styledthemes, I think?). But, I'm guessing that the glance of an expert is gonna beat the crap out of me trying to find it. LOL

Thanks, so much in advance for your help. I hope I don't lose this complete set of promos.

Love & Light,
Gary