i have exactly the same issue with my swift randomly switching to wallpaper and lockscreen. (currently observed on december ota) Often several times in a row.. then again nothing for half an hour...When it happens i have to reenter my pin to unlock it again. I had no chance to test the new ota version if that behaviour changed or not... did not find it in listed fixed bugs.
Back to first post [Fix] - Yes it did work for me. I did receive an ota notification today normally...but my swift had trouble updating to the current release from january (i encrypted it only after the last ota in december). This is fast and easy on linux, but please check md5sum of download before using fastboot. My phone could then load (first again wileyfox screen, then the android guy (with a progress bar) - then to the cyanogen screen - then to a "tooltip" about android updating App x of y.
Keep in mind each loading screen during update still takes a lot of time even if it works! Be patient.before trying to fix it, but over 5 Mins in the first wileyfox screen is probably too long.