We are having the same problem with logins and attribution of sale to staff.
We have two separate POS systems under Shopify plus at our stores, both are not logging in correctly and are not attributing sales correctly.
Since this past weekend the sales would get attributed to random staff, not who were logged in.
Then we started the manual attribution. But even with this the sale gets attributed to random staff.
And, some staff are getting an option to “log in” or “login with pin” that has not been seen before.