Which version of Electrum Android app are you using?
Because the latest version and even the older ones should be able to accept uppercase characters for BIP39 Passphrase compatibility.

Screenshot:


As you can see in the screenshot, you're supposed to scroll-down to type the passphrase below the "Extend seed with custom words" check box.
Your android keyboard app should pop-up, do not use the provided in-app keys which is for your seed phrase above.