A separate appeals court decided that they really don't like the idea of being called on to enforce Congressional subpoenas of former executive branch staff, so they said no a second time, after the whole appeals court refuted their prior decision and sent it back to them.
This will go again to the full appeals bank, which will re-correct the 3 judge panel who are unclear on what their jobs are. These folks would likely rule that SCOTUS oversteps when it interprets constitutionality of laws, too.