Vayne is actually quite garbage against tanks
outside of a 1v1 fight most tanks (ie not shitty Ornn) actually run as a direct counter to Vayne because her short range means she's easily targeted and locked down and then killed by the enemy teams focus fire. Obviously this makes the generous assumption that your team didn't collectively tab out to check Twitter as soon as you went in. If that happens, then yes, you've been countered.
Vayne never appears in tank metas because the optimal ADCs in these games are high range hyper carries who can sit behind their front line and do well in the stability of front-to-back teamfights that are enabled by tanks. Twitch, Tristana, KogMaw, etc. Vayne thrives in chaotic and disorganized fights and she usually shows up (as an actual strong pick and not just her standard popularity) when soloQ has degenerated into fiesta time.
Vayne is more accurately an anti bruiser and is at her strongest when soloQ is laced with bruisers and assassins, creating disorganized fights that she thrives in.
Basically, tanks are not bad in soloQ because Vayne is strong. Vayne is strong because tanks are bad in soloQ.
