So - somehow I got weird words into Electrum Windows and can't recreate the wallet in Android. I'm going to delete and start again.
afaik Electrum seed is slightly different from standard BIP39 seed
the same seed will result different set of addresses because Electrum has its own spec generation
I'm not talking about path derivation or word list but this:
Electrum windows will let me use words not on the list if I click the BIP39 seed option when entering the seed. Android doesn't have this option - that's why I can't enter the Windows Electrum seed into Android and get the "Create" button to enable.
it seems you've generated BIP39 seed in your windows electrum wallet,
so you need to specifically select "BIP39 seed" option when importing in your Electrum android
but again you said the option is not available in Electrum android