Ok, testing a move from v2 firmware 4.9.7.1068 to 4.9.8.1002 (latest) on a single cam.
From within latest Wyze Android app 2.29.1.116 installed fine, don’t see any downside so far. (also fine on 2.22.21 , the android 6 last gasp)
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Updated 5 more (one at a time) with no issues and they are performing well within the app. 
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One cam in a group displayed This device is offline instead of the live thumbnail.
The performance of the cams in Live View is robust, both in Groups and individually. Navigation within a group and between cams is crisp.
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This again, same cam:
One cam in a group displayed This device is offline instead of the live thumbnail.
Remote, so haven’t attempted the power cycle fix, I imagine it will work… 
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Fixed it again…
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Broken again - this time directly after an app crash, upon reentering app and cam group.
‘Restart failed’ returned when attempting ‘Restart Camera’ within app settings.