The lack of declassification is explained by the ways in which DOJ and the Mueller probe have set things up. The Mueller team scoops up every possible doc for their “investigation” ... then while it is pending (indefinitely, going into 2019 now) any declassification would be termed an “obstruction of justice” by Mueller & co. That is why all the calls for Trump to simply order declassification won’t help — he has surely been told that Mueller would treat such an order as an “obstruction of justice” — no matter how perverse that would be.
Sounds like what Strzok/Page/McCabe called an "insurance policy." And if by some miracle the GOP approved a second special counsel to investigate the DOJ etc. its actions would be "obstruction of justice" too.
I solved that problem the same week Mueller was appointed.
Trump could have ordered the release of every document related to Russia Collusion, and to potential crimes by Obama and the Clintons, and to political corruption at the DOJ and FBI.
Then, Trump could have issued a blanket pardon for every name mentioned in those documents.
No trials?
Consequently - no obstruction of justice or political favoritism.
Instead, Trump chose to let the Russia farce metastasize for 19 months, while the Clintons, Obama, and the corrupt Deep State executives walked away without a scratch.