If wallet_1 gives you other addresses apart from then you have the wrong seed (either a word is wrong/different or the order is wrong)
It's impossible for a wallet to be watch only when you create it with a seed phrase so my guess is that you pasted the address instead in the first place.
Go to the console (menu -> console) then paste and see if it shows true or false.
If it shows false then you definitely have a wrong seed.
Code:
DBEutBSzYUzyjDSA1zDWtofPDVJXuepbC3
It's impossible for a wallet to be watch only when you create it with a seed phrase so my guess is that you pasted the address instead in the first place.
Go to the console (menu -> console) then paste
Code:
ismine("DBEutBSzYUzyjDSA1zDWtofPDVJXuepbC3")
If it shows false then you definitely have a wrong seed.
I'm guessing that must be the case. Unfortunately, wallet_1 did show up as 'false' after pasting in that code

I obviously wasn't careful enough when setting this up and am unfortunately paying the consequences of it!
Thanks everyone for you help - appreciate everyone's time and insight with this one. Just a shame there won't be a happy ending!