When I share my outdoor plugs with someone in my house, they cannot power them on. Each time they try, the get “set failed” and it doesn’t work. The plugs work as expected for the owner of them, the person who shared them.
We deleted them from the app and reshared with the same results. App is up-to-date. Firmware is up-to-date.
One weird thing is the the "Activation Date - 12/31/1969
That ain’t right for sure.
No, that ain’t right. The only funky Activation Date I’ve noticed on any of my products (so far) is the date on my Video Doorbell v2 that precedes that product’s public launch date. 
Since you’ve already gone through the exercise of deleting the Plug Outdoors from the app, I wonder if trying to reset them (by holding in one of the power buttons for 5 seconds) prior to setting them up again would have any effect. I’m guessing it wouldn’t, but I don’t know.
One thing I think I’d do is replicate the failure (the error message) on a shared device user’s phone and then submit a log from that phone. Then, as the device owner, I’d open a ticket with Wyze Support that includes that Log ID and the information about the funky Activation Dates. Wyze Support personnel won’t have direct access to the log, but they should be able to communicate the ticket information to the appropriate developers and possibly give you information about that weird date.
I hope you can report back whatever you learn, because I’m genuinely puzzled by this one. Maybe another Forum member has a better idea.