Using Elementary OS 5.0 and having all the same problems. Solution mentioned by @Norbert does not work (as he said earlier) because Pantheon DE is based on GNOME.
This is just unbelievable how it is possible in real life - not to fix this SERIOUS bug for 14+ years. Because handling key combinations on key press is totally incorrect, even every web developer know this. Because Ctrl+Shift and Ctrl+Shift+F is two different key combinations which simply must not and should not be conflicting in any way.
Workaround mentioned by @solarpatrol does not work either, because pantheon’s key shortcuts can’t be set using gnome-tweak tools.
As @Norbert said in xorg865 bug thread. 14 years of doing nothing…
How can even anyone hope about any *nix distro becoming mainstream, if such critical bugs aren’t fixed for DECADES