Confirmed, this still happens with screen 4.4.0-4. Even the work-around works.
It seems to me that there is upstream bug open at https://savannah.gnu.org/bugs/?24076 and there this is treated as a feature request. The report does not describe exactly this ctrl+pageup -situation but ctrl-left-arrow is given as example - this might be the same issue. -- Antti Järvinen
