Sellers with a shipping rule set up for UPS Ground rate lookups may be seeing their E-junkie shopping cart hang/stall (shows a perpetual "loading" spinner) when buyers enter their postal code to calculate shipping. Our Devs are aware of the issue and working on a solution.
To avoid this problem for now, affected sellers can simply delete their current UPS Ground shipping rule(s), and just rely on other shipping rules for USPS and/or custom flat rate shipping rules instead.
The problem is happening because UPS recently retired their public rate API we'd been using for live rate-lookups; they do have a new rate API succeeding the old one, but our Dev team is now having to reimplement our UPS integration entirely from scratch with that new API.
Initially this was causing a "Could not calculate shipping" error when the old UPS rate API went defunct; however, building our new UPS API integration may now sometimes cause our shopping cart to stall out when attempting to calculate shipping on an order that qualifies for any UPS Ground shipping rule.
Unfortunately since we're having to reimplement our UPS integration from scratch, we don't have an ETA for completion of that at present. We will post a followup here to confirm when it's ready, at which time sellers can re-add a new UPS Ground shipping rule if they wish.