I was using an old version of electrum on my mobile. I just updated it to the latest version.
It no longer allows me to create a wallet with a non-BIP39 seed or a failed-checksum BIP39 seed after I check "BIP39".
Charles-Tim is right about the mobile version.
I don't know why developers designed the new version in this way.
This makes the recovery difficult for those who have made a wallet with a failed-checksum BIP39 seed and don't have access to the desktop version for any reason.
As stated by nc50lc above, this is why no one should use a non-standard method for creating a HD wallet.
I just tried also, The Next button can't be pressed when using electrum seed But worked fine when using Bip39 mnemonic seed.
maybe the next update, I just saw development on android in Github.
* just note, for all seed I have been posted is, for example, this means 0 funds and I never used.