Hello,
I use phone Redmi 3 (custom ROM MoKee MK90.0) and Privat24 application, and I get an error "Contents can't be auto-filled" when trying to auto-fill in Russian language system. But if change the system language to English, then everything is ok.
Please, see this video: https://drive.google.com/file/d/12R1m0-pnaJwqa1jMTjObKklVE1TeLLci/view?usp=sharing