Are you on a work issued laptop?
As it could be a IT Policy restriction and secondly if not - are you using Windows 10 Pro?
I ask if you are on Windows 10 Pro - as I have set WU settings by group policy.
So you may be able to get around it by tweaking group policy settings - which I can't say for certain as I don't have an android phone or iphone at hand to test the your phone app.
If you are on Windows 10 home than it maybe due to a cumulative update or it could be another bug in the delayed W10 October update... hard to gauge without more info.
Best way to check which version you have, press Windows key + r and in the run box type in Winver then press enter.
The last thing I can think of is that it's been put back into A/B test / Windows 10 is being persnickety as usual. I had an instance where Miracast and Screen mirroring was working fine on a PC I built and later W10 says that function is not available for the device... when it was working a little while before.
So it could be vast number of things - so more info is required.
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