Views self re-orienting
This happens to us all the time. We always use the original datum planes to orient the model on the drawing, never any geometry. This worked flawlessly since rev.15.
The bug was introduced in rev.20 and usually shows itself on a mold design with detail drawings with many sheets. Since most of our mold designs end up being 15 to 30 sheets we expect to see this on every mold and 85% of the time we do.
This is what we do to get around the aggravation of lost dimensions:
Start your drawing and place the views the way you would like them.
Now move the views around some so Pro re-thinks the position.
Regen the sheet, move the views back to the way you would like them and regen the sheet again.
If the views reorient themselves start over until they seem stable, do this with as many sheets as you need until all sheets seem stable.
After you have all your sheets added save your drawing, close all windows erase not displayed.
Now open the drawing again and look through all the sheets. If any views reoriented then repeat the steps above until the drawing views are clean and stable.
Once the drawing views are stable add your dimensions the way you like them and you should be ok. If you add any new sheets repeat the process for them.
Seems like a bit of work but it is far less aggravating then having to add all the dimensions again, switch views, move them around and clean up the drawings all over again.