To clarify, the state exchange was open and working, but the only thing we did there was see which insurers were available. The idea was originally to deal only with the insurer, but one could only get an estimate of the subsidy, from the insurer we chose. (It seems to me we did not find this on one of the other insurer’s sites, but maybe we did not look hard enough.) The insurer we chose sent one straight over to healthcare.gov (”hot link”) to apply for a subsidy if desired, after a policy was chosen.
Sorry, still doesn't make any sense. A resident of any state can either purchase from the state exchange (and subsidy will be applied if applicable), or purchase from the federal healthcare website (and subsidy will be applied if applicable) if the resident does not have a state exchange. It simply is not possible to "apply for a subsidy" on the federal exchange if your state has an exchange. In fact, "apply for a subsidy" doesn't have any meaning separate from the purchase of an insurance policy.
Which state?