Import wallet doesn't work if words are capitalised or excess whitespace
The way mobile phones auto capitalise the first word and also add whitespace when using autocomplete makes it easy to have a stray capitalised word or trailing whitespace when importing a 12 word seed. Then the wallet won't import, and it won't display a message (as it does if there's not enough words in the seed phrase for instance), and it's not intuitive why.
Edited by Jeremy