I've been experiencing a problem where Adobe Acrobat Pro DC randomly "flips" my files.
Even once I turn them back again and SAVE them, the "space bar preview" continues to display them sideways.
This is KILLING ME
I have the most updated version of the Abode Suite.
uses OS X El Capitan
MacBookPro 2.5 GHz Intel Core i7
Can you share the screenshot of how exactly it looks when you say it flips the page?
Also, check this- Launch Acrobat >Edit> Preferences> Documents> Check "Restore Last view settings when reopening documents"
Close the file also the application and relaunch it, Check if that makes a difference.
How are you rotating them, exactly?