When I open Telegram, I cannot connect to any of MTProto proxies, unless I first connect to my local port-forwarded SOCK5 proxy first. After that, all proxies keep working until I quit Telegram completely (i.e. via the system tray). I tested with both official Telegram binary (latest version) and flatpak. The problem is really annoying.
I’m on Fedora 37 WS. The problem isn’t Telegram’s, as I tested the same static binary on Fedora 36 in a VM, and it works flawlessly.
Did you see that it is a newer Telegram app needed to do the settings as explained on the manual above. Then you should be able to start it automatically. At least as I understood the manual.