keep in mind that some signature verifying tools don't modify the message and when you use new-line in your message it sometimes is \r\n (eg. on Windows) hence the hash is wrong and the signature fails to verify. most tools (like Electrum) do modify it and if you have a new-line (among other things) they will replace it with something else (replace with \n, remove trailing spaces,...).

you shouldn't avoid using something that was added ~4 years ago just because some outdated tools don't support it. you should instead avoid using those tools.