wallet#1 has token#1
wallet#2 has no token#1
- Choose "Send TAU" from wallet#2
- Switch token from TAU to token#1
- Choose "One of my accounts"
- Choose wallet#1 as "From Address" and wallet#2 as "To Address"
- Put in some amount
- Press "NEXT"
- Error comes up

That's probably because initially "Send TAU" was used from within wallet#2 which doesn't have token#1 and the wallet still holds that context