Copy text from .txt file (Text Editor) into Writer. Does not work. Not with mouse menu, not with Ctrl-C crtl-V.
Version: 5.4.4.1; Build ID: 5.4.4.1-1.fc27 (Fedora 27)
Do you close text editor before pasting?
Sounds like the Fedora bug reported at https://bugzilla.redhat.com/show_bug.cgi?id=1410912. Note that bug reports are off-topic for this site.