Stuck at lockscreen (pattern not recognised)

Three days in with a replacement Pixel C, it has stopped recognising my lockscreen pattern. I know it is correct as I use the same pattern on my phone. Wiping the cache has no effect.
I can't use Android Device Manager to set a new password as it detects that the lock screen is already active.
Is there any option other than a factory reset?

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gesture lockscreen security

is there a 6.x.x rom with this feature? I live for this feature

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Yoga 10+ HD: changing lockscreen wallpaper?

So I have a Lenovo Yoga 10+ HD, model B8080-F, on which I've just done a factory reset (to fix a repeated freeze issue), and which is rooted. My current annoyance is that the lockscreen background is stuck on these horrible garish bubbles/balloons, and I can't seem to change it. I've tried opening pictures and setting them as lockscreen background, but to no effect. I'm using Android 4.4.2 (this is the most recent release Lenovo has made available for this model).

How can I change the lockscreen background?

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Lockscreen problem. Please help!

My quick launch shortcuts disappeared from the lockscreen but showing on my homescreen. Can anyone please tell me how do I get them back? Thanks

Sent from my HTC One

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