I'm attempting to let mobile users and steam users link their accounts, I am able to login using google play service (on android) or steam authentication (pc) just fine. However, if I try to use the LinkSteamAccount function on my android device with the same SteamTicket I use to login on the PC, I get the Steam WebAPI error 101 (Invalid ticket) and I get a similar error if I try to use LinkGoogleAccount using server auth code generated by my android device while logged in with steam, the error being invalid_grant bad request. I saw something that maybe those are only good for a single use so that might be a different issue.
I've also tried adding a custom login id to an account that is using google play to login, then logged into that with my steam client successfully but attempting to then link the account using fresh steam credentials also failed with the WebAPI error 101 (invalid ticket).